Continuity mistake: When Maria is hitting Tony while saying "Killer," her hair is across her left cheek. In the next shot, it is completely away from her face. (01:48:20)
Continuity mistake: Near the end of the movie, when George Peppard is talking to Audrey Hepburn in the alley and it's raining heavily, his hair switches between being combed back and combed to the side. Very obvious - this takes place several times.
Continuity mistake: In the cabin when they are coming up with the idea to swap places, Susan has on white sneakers in the beginning of the scene when she is on the bed, and Sharon has on the black Mary Janes. Later in the scene, with no time to change shoes, Susan is seen walking around the cabin wearing the black Mary Janes.
Continuity mistake: When one of the siege towers is rolled over the camera, you can see one of the pushers look for the camera and move to avoid it.
Continuity mistake: At the beginning of their first pool match, Fats' collar goes from buttoned to loose, to back buttoned in only a moment on-screen.
Continuity mistake: When Jake Cutter and Paul Regret ride into the ranch yard, two of the victims are hanging upside down over the gate. In the close-up, there are three arrows imbedded in the gate posts. In the far shots, the arrows are not present.
Continuity mistake: During the scene, when Natalie Wood goes with Toots to make-out point after the dance and jumps in the water, it's supposed to be late at night. When they cut back and forth between shots at the waterfalls and Warren Beatty waiting for Natalie on her porch, all the scenes at the falls were shot in broad daylight, while the ones of Warren on the porch are at night.
Continuity mistake: When Carol and Jerry come out of the water on their day at the beach, they sit at the foot of their beach chairs to dry off, then lay back. Miraculously their towels are spread out over the chairs.