Continuity mistake: Steve McQueen passes the same green Volkswagen at least three times while chasing the black Dodge Charger R/T. This is due to the same downhill portion being shown to us from multiple angles to artificially extend the length of the scene.
Continuity mistake: Minnie gives her the necklace with the tannis root inside and Rosemary holds the chain between her thumb and first two fingers. In the next shot the chain is draped over her fingers. (00:32:15)
Character mistake: The crew many times refers to the sub as a ship - subs are always called a boat.
Continuity mistake: At the beginning, Barbara finds a corpse at the top of the farmhouse stairs with its face partially eaten away. Later, when Ben drags the corpse into another room we get a fleeting glimpse of its face and it shows no sign of decay of any sort.
Revealing mistake: During the bank hold-up at the beginning of the film, one of the pushes a man on the wall. It wobbles like cardboard.