Smokey and the Bandit: It's established early on that Bandid drove a semi before the movie. If that's the case, how did people recognize him when he's driving the trans am? I know he's going through some small towns, but he's going way too fast for people to see him, unless they're really looking. And some most aren't expecting to see him in a car, that should be damn-near impossible.
again SatB: Also from the same movie, the whole reason Bandit got the car was so he could run blocker for Snowman, meaning he'd keep the cops away so Snowman could haul the beer at top speed. Why then does he barely spend any time anywhere near Snowman? He spends most of the movie everywhere else, only really helping him once, with the motorcycle cop.
Jaws: Hooper and Brody take the boat out at night and find Ben Gardner's boat. Hooper just said this area is where the shark likes to roam. Hooper is more than certain this is a big #%$%@$^# shark. Did I mention it's at night, where they won't see the shark until they're inside of it? So why does Mr. shark expert Hooper decide to go into the water. alone. with nothing to protect himself? He even tells Brody nothing will happen. Why? You have no clue where this shark is. It's pitch black out. You find a sinking boat in the EXACT PLACE where you know the shark likes to wander. But you still think it's a good idea to just hop into the water and poke around?
SAW VI: Why did Hoffman go through all the trouble to conceal his tracks (wearing gloves, staying a step away from everyone) in the previous movie to play things so recklessly in this one (no gloves, using Stram's hand instead of just staying invisible, constantly getting suspiciously into everyone's face, etc.)? It's like he forgot all his tactics or just didn't care anymore.