When MacReady checks up on Blair, he already has a noose with which to hang himself.
For some: (just before MacReady dynamites the Blair-Thing) "Yeah? Well FUCK YOU TOO!!"
MacReady pouring his booze into the computer's circuits after losing a round of chess against it.
The whole exchange between Nauls and an irate Bennings.
Bennings; Nauls, would you turn that crap down? I'm trying to get some sleep! I was shot today! Nauls: What? Oh, sure! (reaches over to turn the music down and dismissively pulls his hand back at the last second)
One from the commentary, during which Carpenter is describing the scene where Mac and Norris find the spaceship, and Carpenter gets distracted by Mac's Nice Hat.
John Carpenter: Now Charlie Hallahan is going to describe how long this saucer has been in the ice here, and that the backscatter effect has been uh...uh...melting it down. Great hat, Kurt. Kurt Russel: That kinda commands the scene, doesn't it?