General Hammond summons Colonel Jack O'Neill out of retirement to embark on a secret rescue mission. O'Neill confesses that he disobeyed orders to destroy the Stargate on Planet Abydos, and that scientist Daniel Jackson may still be alive. Arriving on Abydos with his team, O'Neill meets up once again with the scientist, who has discovered a giant elaborate cartouche in hieroglyphics. All signs point to the fact that this is a map of many Stargates that exist throughout the galaxy - a development that makes the dream of the SG-1 team to travel throughout the universe in time a reality.

In the episode "Sight Unseen", Col. Jack O'Neill tells paranoid veteran Vernon Sharpe, who sees aliens, that they were from "Melmac". When Sharpe asks, "Isn't that where ALF was from?" O'Neill says he never saw the show. This is an in-joke, since for most of its run, ALF was in the same time slot as MacGyver, which starred Richard Dean Anderson in the title role.

The first season episode "There But For the Grace of God" is extremely similar to a 1970 Doctor Who story, "Inferno," where a character visits an alternative, military-run Earth, which is about to be destroyed by an "alien" force.

Peter DeLuise has directed a number of episodes, finding a way to appear in front of the camera each time (a la 'Alfred Hitchcock' ). He has played a gate guard, a technician, and even a younger, more handsome version of a character played by his father, Dom DeLuise.

Children of the Gods and the Showtime airings of this series have a line between the words "Stargate" and "SG-1" in the title/logo. The syndicated airings do not have this line.

In Stargate SG-1, Amanda Tapping plays an Air Force scientist who explores other worlds through the stargate. On an episode of "Due South", she guest starred as an Air Force scientist who was apparently studying UFO's on Earth.

During the first season finale, while the SG-1 team is on a Goul'd Mother ship, O'Neill asks Teal'c if the Goul'd "TV" gets Showtime. A reference to the Showtime network, on which the series airs.

In the episode "Seth", there is a scene where Dr. Daniel Jackson is explaining to the rest of SG-1 about the history he has learned about a Goa'uld named Setesh (aka the Egyptian god Set or Seth) on the internet. On the screen with Middle Ages information on Seth, the printed information actually contains information/history from the White Wolf role playing game "Vampire: The Masquerade" concerning a clan of vampires who also worship the Egyptian god Set. In the episode Within the Serpent's Grasp, the original Showtime airing and DVD have a line in which O'Neill tells Skaara/Klorel that something is "bullshit." This word was edited out for syndication.

Stargate SG-1 is the only television series currently endorsed and supported by the United States armed forces (particularly the Air Force).

In the episode Window Of Opportunity, Jack O'Neill can be seen reading a Latin for Novices book, and the author of the book is Joseph Malozzi, the writer of the episode.

In the fourth season episode '2010', an allied alien race called the Aschen are seen developing a program to ignite Jupiter into becoming a star in order to use its moons as planets to be colonized, a homage to the movie and book '2010' which featured a similar climax.

The series has three different opening credits sequences. The first is the original non-clip version, which was used for the premiere and Showtime airings of the show. It was based on the Stargate movie opening credits, panning around a statue of Ra. The second opening credits sequence/set was the one used for syndicated airings. It includes clips from the series. The third opening credits sequence was used on Sci Fi Channel. It is similar to the first sequence through not showing clips, but pans in and out on an activating Stargate. It ends showing SG-1, from the back and in a row of four, entering the Stargate.

The fourth episode of season six, Frozen, features a fourth variation of the opening credits. It shows the sequence from the previous three episodes, with the Stargate being activated, the chevrons locking into place and panning in and out on the Stargate. But part of the screen is now taken up with clips from various episodes.

Originally intended to be one episode, "Jolinar's Memories" was so expensive that the production staff decided the only way to pay for it would be to split it up over two episodes by developing a second part. The second episode, "The Devil You Know", was written. Up to that point, it was almost as expensive for the two-parter as it was for the pilot, "Children of the Gods".

The final two episodes of the show's seventh season were adapted from the script for the feature film Stargate 2.

'Peter Deluise' tries to work the name "Penhall" into every script he directs. This was the last name of his character from "21 Jump Street". In the season 7 episode "Orpheus" Jack calls out to two soldiers; Hanson and Penhall. Hanson was the name of Johnny Depp's character.

The real Air Force Chief of Staff Michael E. Ryan appeared as himself in the episode Prodigy just before his retirement.

While shooting the episode Prodigy, Richard Dean Anderson asked special guest star, Air Force Chief of Staff Michael E. Ryan, "Do you really have Air Force colonels who act the way I do?" General Ryan replied, "Yes, and worse!"

General Ryan's successor, General John P. Jumper, followed the example and will appear in the season 7 finale as himself. He was originally scheduled to appear in an episode filming in April, but the start of conflict in Iraq made him postpone his appearance.

Although they wrote the original Stargate feature the series is based on, Dean Devlin and Roland Emmerich refused an on-screen credit.

In the episode "Secrets", Col. O'Neill tells a reporter "That's O'Neill, with two L's. There's another Colonel O'Neil with one L. He has no sense of humor." In the feature film Stargate, the lead character, whose name was spelled with one L, was played by Kurt Russell and was a much more humorless character.

The Oval Office set used for the show is the same one used in the motion picture X2.

Alexis Cruz (Skaara) and Erick Avari (Kasuf) are the only actors to appear in both Stargate the movie and this television series.

While filming "The Curse," 'Anna Louise Plowman' (Sarah/Osiris) accidentally caused Michael Shanks (Dr. Daniel Jackson) to pass out while she was strangling him.

In the Seventh series episode "Chimera" when Carter gets in the lift with O'Neill, the tune she hums, prompting O'Neill to ask who the guy is, is the Stargate theme.

The prop used to portray the device which controls the Tok'ra memory recall device which looks like a "wand" is actually an electric nose hair trimmer and is used unaltered

In the season 5 Episode "Threshold" General Hammond and Col. O'Neill stand in the observation room watching as Teal'c undergoes the Last Rite. You can see a reflection on the glass below them of the candles in the isolation room, the candles have been arranged into the shape of the initials PD - Peter DeLuise directed this episode.

There are several references made by the character Jack O'Neill (Richard Dean Anderson) to The Simpsons. In the penultimate episode of Season 7, he goes so far as to tell another character: "The analogy is perfect: Burns as Goa'uld." Two other throw-away comments indicate his favorite show airs on Sundays (same day as The Simpsons); at one point, when he realizes it is a Sunday and forgot to set his VCR to tape The Simpsons, he uses Homer Simpson's signature "D'oh!" He also uses other Homerisms, as in episode 1.21, "Within the Serpent's Grasp", when he responds to a Goa'uld long-range visual communicator with "Mmmmmm...cool TV". Richard Dean Anderson is on record saying that The Simpsons is his favorite TV show.

Richard Dean Anderson (Colonel/Brigadier General Jack O'Neill), Michael Shanks (Dr. Daniel Jackson), Amanda Tapping (Captain/Major/Lt. Colonel Samantha Carter), Christopher Judge (Teal'c), Don S. Davis (Major General George Hammond), Gary Jones (Sgt. Walter Davis/Harriman) and Dan Shea (Sgt. Siler) are the only actors to appear in all eight seasons.

The "Tollan Homeworld" shows were shot at Simon Fraser University.

In "The Other Guys", John Billingsley appears as a nerdish scientist who is a trekkie. He talks about "worshipping at the Altar of Roddenberry", and at one point when it appears he will die he says "I might as well be wearing a red shirt" (a reference to the original Star Trek series). Billingsley plays Dr. Phlox in "Enterprise" (2001). A further visual cue is a Klingon bat'leth (sword of honor) on the back wall of Khonsu's ('Adam Harrington' ) throne room.

Apophis was a real Egyptian god, despite many fans' difficulty in finding any information on him. "Apophis" is an obscure Greek name for Apep, the Egyptian god of darkness and night. The native names of Egyptian deities are not widely known except to Egyptologists because most Egyptian mythology was brought to the western world by the Greeks, who altered Egyptian words and names to conform to Greek phonology. For example, Bast the cat-god, was probably pronounced something like "Pasht".

The character 'Jack O'Neill' was ranked #10 in TV Guide's list of the "25 Greatest Sci-Fi Legends" (1 August 2004 issue).

In the season eight episode "Avatar", Carter asks Teal'c has he ever played Doom. He replies, "I play Def Jam Vendetta for which Christopher Judge supplies the voice of the main villain of the game, D-Mob.

The Asgard are voiced by creative staff, cast and crew of the show. Thor is voiced by Michael Shanks, Heimdall is voiced by Teryl Rothery and Loki is voiced by Peter DeLuise.

In the Season 8 episode "Covenant", Alec Colson, played by Charles Shaughnessy, is taken through the Stargate to the Alpha Site. Upon his arrival, he is introduced to a Captain Sheffield. Shaughnessy is perhaps best known to American audiences for playing the role of Max Sheffield on "The Nanny" (1993).

In "Covenant", the logo for Colson Industries is the logo for the Sci-Fi channel (which airs the show) rotated 180 degrees and slightly elongated.

In the Pilot episode, "Children of the Gods" Amanda Tapping ('Samatha Carter') says, "This is how they controlled it. It took us 15 years and three supercomputers to MacGyver a system for the gate on Earth." Richard Dean Anderson played the eponymous lead in MacGyver. According to one account, Tapping ad-libbed the MacGyver reference while reading for the part of Carter, and that was what clinched the role for her.

With its recently announced upcoming ninth season, this series is tied with 'The X-Files' as the longest running science-fiction series on American television.

In the episode "Enemy Within", when Captain Carter (Amanda Tapping) is slammed against the elevator wall, she dislocated her shoulder.

In the seventh season episode "Heroes Pt. 2", the planet where Dr. Frasier is killed is designated P3X-666.

Anachronisms: In Episode: #2.21, an accident sends SG-1 back to 1969. While traveling to New York, they pass through Chicago. The Sears Tower is seen in the skyline. Construction of the tower began in 1970 and wasn't completed until 1973 when it opened to the public.

Continuity error: In "The Fifth Race" when we see O'Neill writing the instructions on how to fix the DHD, he's using a pencil. However when we see the completed instructions later on, they're written in purple ink.

Revealing mistake: In the second season episode "Bane", while exploring a supposedly deserted planet, a car can briefly be seen - through a window - driving past.

Revealing mistake: In the episode "Children of the Gods" Teal'c's supposedly permanent gold serpent marking is upside-down in a scene where he is talking with Jack. There are also some episodes where it is slightly crooked.

Crew or equipment visible: In "Sight Unseen" when Jonas and Sam are investigating the device you can see the light bulbs inside the device.

Revealing mistake: In "Heroes: Part 2" When the film crew are editing their documentary, the time code in the corner of the computer screen doesn't change whenever they play the video

Continuity error: In the episode "The Serpent's Lair Pt2" Daniel is shot by a staff weapon which leaves a bloody hole in his outfit and destroys his walkie-talkie. He is able to drag himself to the sarcophagus, and when he emerges from it his clothes and walkie-talkie are intact, with no trace of blood on them, almost as if he had never been shot in the first place.

Revealing mistake: In the episode "Fair Game" the stargate is activated off-world, but the seventh symbol (point of origin) on the gate as it locks is the same symbol as Earth. Obvious stock shot.

Crew or equipment visible: In Episode 8.05 "Icon" when Daniel is talking to Leda outside near the clothes line, a crew member wearing modern day clothing (thus breaking the "WWII era" theme on that planet) can be briefly seen behind Leda.

Continuity error: In the episode "Solitudes", the second gate has visibly punctured a glacier on its emission side, but Carter and O'Neill were deposited on the opposite side.

Plot holes: In "Tin Man", after the real SG-1 team are found in the lab, the real Col. O'Neil knew Harlan's name and how to open the door, although they purportedly have been unconscious since the electrical discharge.

Continuity error: On the episode "Prodigy", when Major Carter and the cadet step through the Stargate, they have switched places inside the wormhole.

In the SCi-Fi Channel preview for "Cure" (episode 6.12) Peter Stebbings' character, Malek, speaks with a normal voice. In the final episode Malek speaks with the modulated voice common to the Tok'ra and Goa'uld.

Various episodes have been edited for syndication, removing occasional nudity and swear words that were allowed in the first-run Showtime viewings.

The syndicated version of the episode "Within The Serpent's Grasp" does not include O'Neill's quip about whether the Gou'ald long range visual communications device can pick up Showtime.

On the DVD version of the show, the beginning and ending episodes of season seven have had their formats tweaked. As originally aired, Fallen and Homecoming aired as one two-hour episode with one set of opening and closing credits and the only episode titles are seen listed with the respective writers after the opening title sequence. The DVD devides them into the syndicated version of two separate episodes each with their own credits and with the separate episode title on each episode. The reverse is true for Lost City. Originally aired as two separate episodes, the two episodes have been merged into one with one two-hour episode with one opening and closing credits sequence and instead of being Lost City Part 1 and Lost City Part 2, the title is simply Lost City.