An alien archaeologist named Malachi activates an Ancient time-travel device which causes several planets including earth to become stuck in a time loop repeating every ten hours, something that only O'Neill and Teal'c seem to be aware of.
"Window of Opportunity" provides examples of the following tropes:
- Aluminum Christmas Trees: In one loop, O'Neill is riding a bicycle down the corridors of the Cheyenne Mountain facility, presumably one of the things he had always wanted to do and now can without fear of consequences. In some large underground facilities, especially in Europe (the LHC, for example), bicycles are a preferred means of transit.
- And Then What?: Malachi eventually explains that he's doing this to go back in time and be reunited with his dead wife. When he learns that she tied of an incurable disease, O'Neill uses this trope. Could Malachi really watch someone he loves die again?
- Anti-Villain: Malachi isn't a particularly bad guy, he just wants to figure out how the time machine works so that he can see his dead wife again. Unfortunately, he's so obsessed that he doesn't much care about dragging fourteen other planets into the time loop with him, but is still visibly shocked when learning about doing so.
- Arbitrary Skepticism: Before it starts buckling down to montages, half the episode is about Jack and Teal'c trying to get everyone else to accept that there's a time loop and help them end it.
- Big Damn Kiss: O'Neill takes the opportunity to lay one on Carter during one of the loops. In the control room, in front of Hammond no less.
- Boredom Montage: During the loops where Daniel is trying to teach O'Neill and Teal'c Ancient so that they can help him translate the writing on the device. Their antics get increasingly ridiculous with each successive loop until Daniel turns around at the end to find them both juggling wadded-up balls of paper with utterly deadpan expressions. Then he points out that technically they can do whatever they like without consequences, owing to the nature of the loop. Things get exponentially wackier from there.
- Buffy Speak:Daniel: So Sam was setting up instruments, and where was I?
O'Neill: You were by the altar deal with the guy.
Daniel: Right, you're gonna need to be a little more... specific.
- Butt-Monkey: Daniel gets knocked over by Siler crashing into him in several loops. After a few loops, O'Neill finally intervenes, heading to Daniel's office/room to per-emptively meet him.O'Neill: You're better off in here.
Daniel: (a little confused at Jack's arrival) I was just about to look for you..?
- Continuity Nod: It's pointed out that O'Neill should have at least a passing familiarity with the Ancient language, since he had their entire database downloaded into his brain in "The Fifth Race".Daniel (to O'Neill): It should [look familiar]. It's something that you spoke for a few days.
- The Door Slams You: It's revealed that Teal'c begins every single loop with some hapless airman opening a door in his face. In at least one loop he's lost patience enough to slam it right back into the guy.
- First-Name Basis: In one of the loops that Jack is taking off, he walks into the dialing room in his civilian clothes and hands Hammond his resignation by saying, "Here, George."
- Foreshadowing: At the very beginning of the episode, before the looping starts, Daniel and Malachi discuss possible translations for a line of text on the device:Malachi: "Conqueror of time".
Daniel: No, in this context I'd say more like "master of the uncertain past".
- Gilligan Cut: During one loop, when Jack insists to the team that he and Teal'c are caught in a "Groundhog Day" Loop. He says he doesn't know what's going on...Jack: ... but I do know for a fact that there's no point in having ol' Doc Fraiser examine us again!
(Sam and Gen. Hammond share incredulous looks, then cut to Jack sitting in sickbay with Dr. Fraiser examining him.)
- "Groundhog Day" Loop: The whole point of the episode. O'Neill even mentions the Trope Namer at one point.
- Hidden Depths: O'Neill eventually takes advantage of the loops to learn pottery.
- I Never Told You My Name: O'Neill is able to confirm for certain that Malachi is also aware of the time loop when he refers to Carter by name during the team's second visit to the planet, despite the fact they were never introduced in that particular loop.
- I Warned You: O'Neill at one point comes up with what he thinks is an ingenious idea to record Daniel's work on the translation, only for Daniel to point out that the recording will be erased every time the loop restarts, which leads to this exchange:Teal'c: [smugly] Did I not say that your plan would be unsuccessful, O'Neill?
O'Neill: Careful! Be careful.
- Impossibly Mundane Explanation: During the first loop, when O'Neill starts correctly guessing what Carter is going to say during her briefing, she points out that it's possible he just read her report. Daniel's reaction suggests this is the most ludicrous thing he's ever heard, and the rest of the team — including O'Neill — seem inclined to agree.Carter: Maybe he read my report.
Daniel: Maybe he read your report???
- Mood Whiplash: The episode is mostly comedic, but it takes a turn for the depressing towards the end when it's revealed that Malachi is trying to go back in time to see his wife again. Particularly when he tells O'Neill that he could never understand, to which O'Neill very emotionally responds that he lost his son.JackI know how you feel.Malachi: You can't!Jack: I lost my son! I know! And as much as I....I could never live through that again.
- Motor Mouth: Once the translation is complete, Hammond asks whether the time loop can be broken, prompting Daniel to launch into a lengthy, rambling explanation which O'Neill eventually interrupts with an exasperated "Yes, sir."
- Mundane Utility: At one point O'Neill and Teal'c take to hitting golf balls through the Stargate.O'Neill: How far is Alaris, anyway?
Teal'c: Several billion miles, O'Neill.
O'Neill: That's gotta be a record.
- My God, What Have I Done?: The expression on Daniel's face when he realizes he's just told O'Neill and Teal'c they can get away with doing whatever they want without fear of the consequences.
- Out-of-Character Alert: One of the reasons Carter starts believing the time loop is real is that O'Neill is actually using proper scientific terms in their correct context.Carter: When was the last time you heard Colonel O'Neill use terms like "subspace field" and "geomagnetic storm"?
Hammond: Good point.
Carter: And he actually used them correctly... for the most part.
- Parodies for Dummies: At one point O'Neill is shown reading a book titled "Latin for the Novice". The author is "Joseph Mallozzi, Ph.D."; Stargate SG-1's writer/producer.
- Repeated Cue, Tardy Response: On an early cycle, Jack tries to prove to Sam and General Hammond that that is what's going on by predicting that another SG team will come back early because one of them fell and broke his ankle. Jack's guess was about a minute early and he used this trope when it didn't happen when he said it would.
- Rhetorical Question Blunder: When O'Neill is trying to prove to the others that Malachi is responsible for the time loop:O'Neill: What kind of archaeologist carries a weapon?
Daniel: Uh, I do.
O'Neill: ...Bad example.
- Sanity Slippage: O'Neill begins to suffer from this after going through an unspecified number of loops, leading to his infamous meltdown in the commissary.O'Neill: [drawing on his plate with ketchup and mustard] I'm telling you, Teal'c, if we don't find a way out of this soon I'm gonna lose it. [off Teal'c's blank look] Lose it. It means go crazy. Nuts. Insane. Bonzo. No longer in possession of one's faculties, three fries short of a Happy Meal... [holds up plate to reveal a crazed smiley face drawn in ketchup and mustard]... WHACKO!!!
- Ship Tease: In one of the loops, O'Neill hands in his resignation to Hammond and kisses Carter, who practically melts into his arms.
- Some Kind Of Forcefield: Malachi is revealed to have set one up around the device at the end of the episode, which Teal'c finds out the hard way by walking into it face-first.
- Time Machine: The Ancient device was supposed to be this; it's revealed that it was originally built to send them back in time so that they could find a cure for the disease that was wiping them out, only it never worked and ended up creating a ten-hour time loop instead.
- Writers Cannot Do Math: When hitting golf balls through the Stargate, Teal'c comments that Alaris, the planet they dialed was several billion miles from Earth. That would put Alaris somewhere near Pluto. Heck, a light year is about 5.8 trillion miles and the closest star to our sun is Proxima Centauri, which is 4.2 light years away.