"We alter this timeline, and the future is already different. We could set into motion a spiral of changes that we could never fix."
— Lt. Col. Samantha Carter
Daniel inherits Catherine Langford's estate after she passes away, and stumbles across evidence of a working ZPM in Ancient Egypt under Ra's rule while going through her things. SG-1 plus O'Neill use the Ancient Time Jumper to travel back in time and retrieve the ZPM, but the plan goes wrong and they end up stranded in the past, inadvertently altering history as in the process. In the alternate timeline that results, the stargate is never discovered, and very different versions of Daniel Jackson, Samantha Carter and Jack O'Neill are approached by the Air Force after a tape that seems to feature them turns up on a dig in Egypt...
"Moebius, Part 1" provides examples of the following tropes:
- Abhorrent Admirer: McKay is this towards Carter in the alternate timeline, grabbing her ass literally moments after meeting her.
- Adventurer Archaeologist: Lampshaded by Catherine's niece when she meets Daniel at the beginning of the episode.Sabrina: You know, my aunt used to talk about you all the time. It's funny, I always used to picture some Indiana Jones type with a bullwhip and a pistol, chasing bad guys through some ancient temple.Daniel: Yeah, well, I generally leave the whip at home so...
- Aroused by Their Voice: McKay proclaims that could listen to Carter read the phone book.
- Bus Crash: Catherine Langford dies offscreen after being absent from the narrative since season 2, with the estate that she leaves to Daniel kickstarting the plot of the episode.
- Call-Back:
- Sabrina gives Daniel back the Eye of Ra pendant that he borrowed from Catherine in the movie.
- Samuels approaching alternate O'Neill in his boat after the tape is found is reminiscent of the scene where O'Neill was first approached to come out of retirement in the pilot.
- Alternate Carter is able to pinpoint the location of the Antarctic gate by the same method that Daniel used in "Solitudes".
- Changed My Jumper: The team immediately change into era-appropriate robes after arriving in Ancient Egypt.
- Chekhov's Gun: The Ancient time machine found on Maybourne's planet is put to use.
- Continuity Nod: As part of the Running Gag throughout the series, Alternate O'Neill's boat is named "Homer", showing even in this timeline, he really enjoys The Simpsons.
- Continuity Overlap: With the tail end of the first Season of Stargate Atlantis. "Moebius" takes place after "Letters from Pegasus", so the SGC is now aware of the impending events of "The Siege". Reopening the Gate to Atlantis to reinforce the Lost City is one of the driving engines of the 'Recover the ZPM' plan.
- Crazy Enough to Work: Subverted; Daniel invokes this to convince the others that travelling back in time to retrieve the ZPM is a good idea, but the plan fails and they end up stranded in Ancient Egypt with no way to get back to their own time.
- Dénouement Episode: The entire two-parter counts as this, as it's mostly a standalone story after the main story arcs involving the replicators and the Goa'uld were resolved in the previous three episodes. The plot of this episode actually has much bigger consequences for the Atlantis expedition, as they're the ones who need the ZPM.
- Description Cut:Alt!Daniel: We need someone who's willing to go to bat for us... Someone who they can't say no to.(Cut to alternate O'Neill hammering loose boards on his boat)
- Dressing as the Enemy: Teal'c briefly disguises himself as one of Ra's guards to sneak into the temple and steal the ZPM.
- Early-Installment Weirdness: Carter's schematic graphics of the Daedalus at the beginning of the episode. The design is closer to the Prometheus template, but will be fully redesigned for its formal debut on Stargate Atlantis the following Season.
- For Want Of A Nail: The original team's meddling with time somehow leads to Ra taking the stargate with him when he leaves Earth, leading to some serious changes in the alternate timeline that's created as a result. Some of the most notable:
- Daniel is somehow even more of a nerd than he was at the beginning of the series, and is reduced to teaching English as a second language after destroying his academic career with his outlandish theories about the pyramids that were never proven true in this timeline.
- Carter never joined the military and works at the Department of Aerospace Research in a job that essentially boils down to proof-reading the work of other scientists. This version is also unexpectedly dorky and lacks the self-confidence possessed by "our" Carter.
- O'Neill never re-joined the Air Force after his retirement and makes a living as a charter boat captain.
- Kinsey is President, while Hayes is Secretary of the Interior.
- Hammond is only a one-star General, while at this point in the prime timeline he has three stars.
- This version of McKay isn't allergic to citrus, and Paul Davis has a mustache.
- Frontline General: O'Neill accompanies the team on the trip to Egypt, since he's the only one who can pilot the Time Jumper.
- Hard on Soft Science: McKay gets in a dig at alternate Daniel's chosen fields when he questions McKay's attempts to get the Time Jumper working.Alt!McKay: I'm sorry, what are your areas of expertise?Alt!Carter: Astrophysics.Alt!Daniel: Archaeology.AltMcKay: And I would listen to you because...?
- Hitler's Time Travel Exemption Act: Carter extends this to Ra when she prevents O'Neill from shooting him in the past.O'Neill: Let me do it now, I won't have to do it in 5000 years.
Carter: You can't do that. There's no telling what effect it might have. - Innocent Innuendo: One of Alternate Daniel's ESL students says "you make me so hot" when attempting to talk about the weather.
- It Always Rains at Funerals: It's raining heavily during Catherine Langford's funeral.
- Jumped at the Call: The alternate Carter and Daniel are both thrilled by the discovery that they're "supposed" to be on a team of intergalactic explorers, possibly as a result of how crappy their actual jobs are in this timeline. By contrast, alternate O'Neill doesn't want to know.
- Kick the Dog: Ra has one of his followers executed for bringing an offering that displeases him.
- Lost in Transmission: The tape that the original team make for their future selves in the event that they change the timeline cuts out just as Daniel is about to explain what the ZPM is for.
- Male Gaze: Dr Hersfield stares at Carter's breasts so blatantly that she actually looks down with a faint look of disgust on her face. This being a less self-assured Carter though, she just accepts it as opposed to planting one on his nose.
- Mistaken for Romance: When the alternate Daniel and Carter first approach O'Neill on his boat, he asks if they're a couple.
- Not That Kind of Doctor: The first meeting between alternate Daniel and Carter:Alt!Daniel: Dr. Daniel Jackson.Alt!Carter: Dr. Samantha Carter.Alt!Daniel: Oh! Uh, PhD.Alt!Carter: Oh, me too.
- Note to Self: After getting stranded in Ancient Egypt, the prime team decide to record a message for their future selves using Daniel's video camera in case they don't make it back and the timeline is changed. Daniel also carves a tablet in hieroglyphs that only he will be able to read, giving among other things the location of the second Earth stargate.
- Oh, Crap!: When the original team get back to where they left the cloaked Time Jumper and realize that it's now heavily guarded by Ra's forces after a sandstorm uncovered its position, preventing them from getting back to their own time.
- Personal Effects Reveal: Daniel realizes that there was a functioning ZPM in Egypt five thousand years ago after going through Catherine's effects and finding a picture of it at the beginning of the episode, giving him the idea to go back in time and get it.
- Ragnarök Proofing: Other than needing the battery charged, Daniel's video camera is fully functional when it's uncovered in the alternate timeline five thousand years after he stashed it at the site of the dig. Possibly justified, however, since it was kept in a Goa'uld canopic jar, which have previously been shown to keep a symbiote alive indefinitely so long as it remains intact.
- Sarcasm-Blind: Dr. Balinsky, evidently.
- Self-Deprecation: Carter's infamous "reproductive organs" speech from the original cut of the pilot is mocked.Alt!Carter: Just because my reproductive organs are on the inside instead of the outside doesn't... God, that's horrible! Who would ever say that?!
- Shout-Out: Alt!Rodney wears a Mr. Fantastic T-Shirt.
- The Slow Path: Once they realize they're going to be stuck in the past indefinitely, the team devise a plan to ensure that the ZPM makes it back to their time even if they don't, by burying it at the site of a known archaeological expedition taking place in the present day.
- Trick Dialogue: Alternate Carter is first introduced delivering an impassioned rant to her boss for unfairly profiting off her work... and then the camera cuts away and we see that she's actually rehearsing the speech to an empty chair.
