"Helsinki": Easygoing Arthur throws a bowl of mostly chocolate was-going-to-be-cake straight in his aunt's face because she nearly made Carolyn cry. This is pretty big for someone whose default mood is "obliviously cheerful".
MJN's escape from Douz Airfield not only creams the thieving airport manager, it is also one of the most magnificent escapes ever carried out by a dilapidated sixteen-seat aeroplane.
Juteau: You do not have clearance! Repeat, do not have clearance to take off! Douglas: Take off? Martin: Who said anything about taking off? Carolyn: Wouldn't dream of it! Against the law, you know. Douglas: Plus we've got nothing like enough fuel to get us there... In the air. Martin: On the ground, though— Carolyn: —taxiing down the long straight highway to Kebili— Douglas: —we should be fine! Martin: Right hand down a bit, Number One! And be sure to indicate when joining the road.
Martin - Martin - landing GERTI on one engine, in a cross wind, after a bird strike. Suddenly, in their worst ever crisis, the pilots are totally confident, Douglas talks to Martin like a Captain and Martin lands the plane so well that Arthur and Carolyn "thought Douglas must have done it" (which is a good thing).
Arguably, the whole last ten minutes of 'St Petersburg', with Carolyn, Douglas and Martin rallying to defeat Gordon due to his attempt to steal GERTI and also his disregard of Arthur and his gift of Gordon's Gin ("So whenever you want to know which gin is yours, itíll be the one with your name on it, a-and whenever you want to know what your name is itíll be written on your gin!").
Douglas: Mr Shappey finds he has use for some alcohol. Do you happen to have his bottle of gin? Martin: Right here Douglas. I know itís his, because itís got his name on it. Have you decided you like it after all Mr Shappey? Gordon: Gimme it here! Martin: Certainly, and er, whatís your present for him? Gordon: What? Martin: Itís usual to exchange presents isnít it? What have you got for Arthur? Gordon: Nothing! Martin: Oh dear, how embarrassing for you.
Later in the same episode:
Carolyn: Get off My Jet Now!
Martin's speech to his Swiss Air interviewers in "Yverdon-Les-Bains", after he learns that the whole interview is a sham and they never even considered hiring him:
Martin: You wanna hear [a flaw] you've never heard before? I'll tell you one that I guarantee you have never heard before. [...] My biggest weakness as a pilot is that I'm not very good at flying aeroplanes. [...] I mean, I'm good enough. Like the sim said, I'm adequate. Adequate to the task. But I don't do it easily; it's not second-nature to me. On your scale from one to ten, if one is the bare minimum competence, I'm about a four. And I used to be a one. No, I—I used to be a zero. And then I took my CPL again ... and then again ... and then I was a one, and then a two, and then a three, and now a four. And I'm not finished yet. And that's why you should employ me. That's why you'd be lucky to employ me! Because if you're not naturally good, if you can't rely on just knowing how to do it like Doug—like some people can, then you have to, well, you have to be a perfectionist, actually. And I am one! And that's why, even when you've turned me down, I'm gonna keep on applying. Because flying is the perfect job, and I won't settle for a life where I don't get to do it!
Douglas and Carolyn one-upping Simon Crieff with their tales of Martin (especially the, uh, souped-up version of the landing in St. Petersburg) arguably count. Especially because of Martin's exhilaration at the end.