It Takes a Thief (1968) - 5 major mistakes

Audio problem: When Katrina walks out of the building at the end and crosses the street to Dover's car, the sound of her boots on the pavement doesn't match the actual movement of her feet at all.

Continuity: Ortega takes Mundy's shoes (with lock picks hidden in the heels) and locks him up. Mundy soon has the confiscated shoes back on again, though, even before he escapes the cell.

Continuity: The professor translates the two Chinese symbols from Mundy's brass rubbing. Then he's shown a Chinese business card, and states that the 12 symbols on the card say the same thing. But not one of the symbols on the card matches the first two from the paper.

Continuity: When the airline pilot enters first class to announce the baggage search, we see only 7 seated passengers and many empty seats. When the angle reverses, there are instantly 15 people seated, and almost no empty places.

Factual error: Gino commits a murder using a six-shooter with a silencer attached, and his shot doesn't make any noise. But it should have. Though it's a long-standing Hollywood cliché, a revolver with a silencer wouldn't be silent at all. Unlike automatic weapons, revolvers are open-chambered, which allows sound to escape. They can't be muffled with a silencer.