Plot hole: When the President of the United States attends a public gathering (such as the SuperBowl) the level of security is extremely high. So why wasn't Mason's delivery on the day of the game checked for explosive devices?
Plot hole: When Diana turns up at her director friend's house she finds it crawling with cops as his girlfriend Christie has been murdered and the house is now a crime scene. She explains she lent Christie a coat and is there to pick it up - and a cop helpfully finds it on the floor and hands it to her. Are we to believe that a homicide policeman will hand over an artifact from a murder scene to an unidentified woman without making any attempt to confirm her identity, or even if the coat is even hers!? They don't even ask.
Plot hole: When Hooper and Chief Brody are trying to get the Mayor to re-close the beach after finding Ben Gardner's boat, they fail to mention they also found Ben Gardner's severed head. The Mayor would be forced to re-close the beach if yet another confirmed shark fatality had been mentioned, but Hooper and Brody never bring that important detail up. [This is still a mistake, but the explanation for this is that the scene where they find Ben Gardner's head was not in the original script. Originally, they just found his boat. Spielberg felt the scene needed a little more shock value so they shot the part with the head in a swimming pool long after the main filming had been completed.] (00:50:20)
Suggested correction: First off, it wasn't a severed head as you can still see the body attached to it, and second, what difference would that make? Two people and a dog already died, with the death of the Kitner boy being witnessed by several people, and the beaches still stayed open because the mayor was too stupid to close them. Not only that, but during the scene you mentioned, I believe it was Hooper who said that THREE incidents had occurred BEFORE the third killing takes place on-screen.
And not only that, but the mayor witnessed Hooper saying that the shark they caught was not the same one, or at least it was possible that it wasn't. Either way, shark attacks were happening, but the mayor did nothing about it.
Plot hole: The fearless trio is in the watch tower when the hillbillies set fire to it. Realizing their fate if they stay, the three then jump out the window and onto nearby tree branches in order to escape the blaze. After escaping the towering inferno, it seems that the fire dies immediately. These three don't go far after jumping and are in the trees for some time. Shouldn't there be a great glow and lots of noise and smoke from the fire as the watch tower burns down? (00:53:45 - 00:56:00)
Plot hole: Bond would not have had (nor taken himself) time to lay a complete and careful clown make-up while changing clothes in the circus trailer.
Plot hole: When the deputy arrives at the sheriff's house, Michael gets out and leaves the door open. The deputy comes out to the car and sees it open. And he thinks nothing of it, despite knowing he didn't open it. Logic would say, "Well someone else opened it."
Plot hole: Following Glen's death, Nancy tells her father to come across the street in 20 minutes to catch Freddy. She then goes to her house, checks and sets her alarm clock, and proceeds to rig the entire house with booby traps, including filling a light bulb with the contents of several shotgun shells, and has a heart-to-heart talk with her inebriated mom. When she gets back to her room to go to sleep, she checks her clock again. The time on the clock has advanced only ten minutes, not nearly long enough for everything she did.
Plot hole: When Iris Henderson and her two friends arrive at the hotel, Iris orders dinner and asks that it be sent up to "our" room. The waiter arrives when the three are changing. But later, when it's time for bed, Iris says good night to her friends, who leave her alone in the room (as she must be for the sake of subsequent developments).
Plot hole: The original ending planned was a massive tropical storm/water based chase scene. However, this was decided to be too expensive, and was switched for a cheaper, and some say weaker ending. Nonetheless, in Nicholas Cage's final speech, he says "I keep thinking about that tunnel, and what would have happened if I'd drowned." This makes no sense, given that in the new ending he came nowhere near a tunnel or drowning.
Plot hole: George Lebay says that his brother died "6 weeks ago" inside Christine and that's why he's selling it. Later that evening after Arnie leaves his house and goes to Darnell's, Will Darnell says he "knew a guy who owned a car like that" and "the bastard killed himself in it." If it's only been 6 weeks since his death, shouldn't Darnell have recognized the car? It's not like there were lots of red Plymouth Furies (custom order color) running around the small town, let alone the USA, even in 1978. (Also considering how production even had a hard time finding them for the movie).
Suggested correction: He says he knew a guy with a car like that. It doesn't have to be the same colour or even the same generation. Just a Plymouth Fury.
Darnell basically said he knew THE brother of Lebay, not just some guy who owned a similar car. Darnell described Lebay's brother based on the story. Again, it was him, not just some other guy.
Plot hole: In the last car-chasing scene, the timekeeper had switched his car to chase them, then how could Justin Timberlake get the timekeeper's salary (a day's time) from a car that the timekeeper picked up from the streets?
Suggested correction: I think it is the car of another time keeper. Hence, it may have a time transfer system.
Plot hole: When Bond and Scaramanga are duelling, Bond has no tie or jacket on. After Bond drops his gun and gives his hiding place away, he somehow has the time to not only crawl back onto the staging but to move the wax replica of himself and also to put on the dummy's jacket and necktie.
Plot hole: It has already been mentioned that a certain shot reveals that Sidney isn't wearing the bullet-proof vest when she should be. Further to this, most of the shots in the climax sequence make it impossible for her to be wearing one, as you can see the contours of her chest throughout. A bullet-proof vest would flatten the appearance of this.
Plot hole: When Hauser/Quaid returns to Mars, some of the people that knew him before as Hauser call him Quaid. (00:45:40)
Plot hole: During Howard's flashback the viewer sees from his point of view the two SS agents who had been following Enrique fire multiple shots at the now revealed Spanish police officer as he was talking to another police officer (Javier) who had just approached him. The scene ends leading the viewer to believe Enrique was killed by the SS agents. However, in the final scene when it's revealed that he was in fact killed by Javier the SS agents significant fire (9 shots I counted) and presence is completely forgotten. (00:40:00 - 01:12:00)
Plot hole: The government would have no chance of hiding the existence of the comet for a year. Most comets are discovered when they are very faint, literally thousands of times fainter than Wolf-Beiderman when Leo found it. Long before the events in the film take place, probably even before the government itself would be notified, the comet would have been discovered, an orbit calculated, and people panicked. The whole premise of the first half of the movie is thus based on flawed logic.
Suggested correction: Only 3-4% of the visible universe has been discovered. Meaning this comet could have been discovered much later.
Plot hole: At the end, when Chris finds the informant's phone, he sees that there are 2 voicemail messages. Instead of listening to them, he calls the last number, which reveals Abel is responsible for the break-in when he answers and in turn reveals to Abel that Chris knows about the break-in. It would make more sense to just listen to the voicemails, as Chris became immediately suspicious when he saw them. Considering Chris called the last number, he must have known that the last number was also the person who left the voicemails. Very deliberately done to bring realizations between Chris and Abel for a climax.
Plot hole: When the bomber is surrounded at the end he gets shot in the leg but manages to get away from all of the police that were surrounding him. They were literally an arm's length from him.
Plot hole: In the institute, Will's friend gets out of his room to get the guard's keys. He couldn't have gotten out of his room because there isn't a handle or door lock inside the room.