Paranormal Activity 3 (2011)

Revealing mistake: While driving the Mercedes to the house of grandma, the gauges on the dashboard show speed is zero and the engine is cold.

Other mistake: While Dennis is editing one of the video tapes, there's one on a table labeled "89" even though the film takes place in 1988.

Continuity mistake: In the first PA, Katie says that the "ghost" was in front of her bed, however we never see it in PA3.