Before Juan and Penolope start kissing, she gives him a hat, and it falls to the floor. When he remembers he has to make s'mores, Penolope doesn't pick the hat up, but after he runs away, she drops it to the ground.
When Cliff is killed in the maze, the killer slices his stomach with his right hand going from right to left. In a later scene, Hank explains he is looking for the left handed killer. He states the cut on Cliff was "left to right".
While being chased by the towards the end of the movie, the camera pans up to reveal a dirt cliff as the dead end. But as each character jumps, it shows them jumping off a white rock cliff into the ocean.
Towards the end of the movie, when they come out of the club house just after Juan breaks the hot tub, the watermelon is behind the pretzel, then in the next shot the pretzel is behind the watermelon, then in the next shot the watermelon is behind the pretzel again.
When Juan, Penelope, Jenny and Lars are running from the killer in the jungle toward the end of the movie, when they go into the jungle it is night. The next shot shows The Sun just starting to rise above the forest trees. In the shot that follows, the three are running in the jungle in broad daylight.
The goof item below may give away important plot points.
At the end on the speedboat, Lars dives underneath to put on the working propeller. He then surfaces and hits the killer on the head with a propeller, which then falls under the dashboard area. Earlier on, when Lars found the boat, he brought the broken propeller to shore!