Chekhov's Gun: Early on, Nick mentions a new laser pointer he bought Chet. During the climax, Chet uses it to trick Dwayne and Travis into thinking Nick's got a sniper backing him up so that they can escape.
Kate mentions early on that she lives very close to the pizza place Nick works at. Later, Nick takes advantage of the short distance to sneak off to talk to her while Chet thinks he's in the restaurant.
Good All Along: After Chongo decides to kill Duane, he breaks into his house and runs into The Major. The Major refuses to tell Chongo where Duane is, even after being told Chongo was hired by Duane to kill him. The Major's pretty much just your basic, fed-up-dad-with-layabout-son type of character, he's just more mean about it because he's a retired Marine.
On the other hand, this is Truth in Television for many teachers. They'll read the note out loud in order to embarrass a student into not doing it again.
Karma Houdini: Dwayne and Travis don't get the money, but they survive their injuries, and even manage to open up their tanning salon/prostitution ring.
Nick & Chet get away with robbing a bank.
Well they don't get caught or identified but they ended up with only an ink bag... which will likely get them busted and with the bomb destroyed they have little evidence proving they were coerced, but they still got away scot free for stealing their neighbors car and trashing it.
Juci, who came up with the idea of murdering The Major in the first place and who actually does try and kill Chet and Nick also gets away scot free and without even the severe injuries the other surviving bad guys end up with.
Minion with an F in Evil: Travis isn't comfortable with the idea of killing The Major, or of people actually getting hurt in their attempt to get the money. On the other hand, he doesn't hesitate to kill Chongo, albeit in self-defense.
Shaggy Dog Story: The money that all of the characters had been fighting for during the entire length of the film was rendered useless the moment it was taken out of the bank due to a hidden dye bomb. However, nobody figures this out until they actually open the case at the end of the film.
What the Hell, Hero?: Chet and Nick give this to each other multiple times, with Chet angry about Nick sleeping with his sister and Nick angry about Chet telling someone about Nick's mom having an affair, which led to word of it spreading around and leading to Nick's parents splitting up.
Travis later gives this to Dwayne, while changing the codes on the remote detonator, after Dwayne plans on cutting his losses and blowing Nick up.