Revealing mistake: When Martin is at the rest home, he gets a drink from the water fountain and it sprays him in the face. You can plainly see the spray isn't coming from the fountain itself.
Revealing mistake: In the scene where Laura deliberately breaks the boardwalk lamps, she picks up rocks from the beach and then throws them at the lamp bulbs. However, the first rock thrown misses the lamp bulb completely and in fact, passes behind the lamp post. Of course, the bulb breaks anyway because the explosive charge used to break the bulb was detonated remotely.