well since most of the ones i can think of have already been mentioned,and i don't really watch a lot of movies, there's not much for me to say, except for maybe the one in the shining. Yes jack went crazy and all that, but it doesn't explain how he just froze to death in the maze, he didn't even go that far from the entrance, 2, maybe 3 turns in and away,while his son runs deep into the maze and yet easily finds his way back out, while somehow gets stuck out there for the night and freezes to death, like he didn't only go insane, but lost his intelligence as well apparently...still love the movie though.
Aaron Sylvester said:
The biggest plot hole ever is Bruce Banner's pants. Seriously, what the F are those pants made of??
The biggest plot hole in the Harry Potter series is the goddamn Time Turner. Where the hell did that thing go and why wasn't every character (good and evil) seeking to find it and use it? It seemed to be the single-most powerful artifact in the entire story.
Also regarding the Fusion Reactor in Dark Knight Rises, I totally agree that you can't turn a fusion reactor into a bomb in ~15 seconds. You just can't, it's not how reactors work. When a fusion reactor destabilizes it melts down and releases a whole bunch of radiation into the surrounding area. It does NOT explode and vaporize everything in a 6 mile radius, because it's not a goddamn nuclear bomb...it's a reactor. They are built completely differently.
While i can't say anything about Bruce' pants(maybe magic since it's the marvel universe...meh,let's go with that), and you've already explained how fusion reactors work. the time-turners weren't gone after for 2 reasons.
1)due to the use of one, when a person goes back in time, they have a chance to run into said past self. since the past one wouldn't yet know about the use of a time-turner, they're like to shoot first and ask questions later at seeing a double, since it would be assumed polyjuice potion over time travel.
2) I don't know if it's shown in the 5th movie since i stopped watching after the 4th one, but in the book at the fight in the ministry, one of the spells used by a death eater destroys the place where the time-turners are stored when not in use, while i'm sure there's some still around, that's where the majority of them were so they assumed they were gone.