Continuity: Milo Perrier tells Sam Diamond "I'm not a Frenchy... I'm a Belgie" referring to the fact he is from Belgium and not France. However, in discussing Twain's annual poodle hunt in France, he implies that's his home country, and he says, referring to himself, that you should "never underestimate a Frenchman's nostrils."
Continuity: Sam Diamond extends his arm and points at Jessica Marbles at the dinner table when she deduces there are "two dining rooms". In the next shot, he is pointing with his opposite hand.
Continuity: When Inspector Milo Perrier is being driven to the home of Lionel Twain, the candy bar he is eating changes size inconsistently between shots.
Continuity: When Lionel Twain is leaving the dinner table, left arm alternately up/down between shots.
Continuity: When the Gargoyle falls on Inspector Wang and son, the position of the debris changes between shots. The first time the large "chunk" is on the steps. On the next shot it is down the steps next between Wang and son.
Continuity: When Milo Perrier is in the kitchen inspecting the dead body of the butler with Jessica Marbles and Inspector Wang, he discovers a note in the butler's hand. When he removes it, it gets ripped. When we see him in the next shot with the note, it is no longer ripped.
Factual errors: When the "deadly snake" is placed in Wang's bedroom, you hear loud hissing and a rattlesnake's rattle. Later, when Wang and son confront Bensonmum they present a constrictor.
Factual errors: In the beginning when the screws in the door hinge are loosened, they make the door creak; in reality doing so would only make the door not close properly.
Errors made by characters (possibly deliberate errors by the filmmakers): At one point in the dining room Milo Perrier is referred to as Marcel Perrier. Marcel is Milo Perrier's chauffer.
Audio/visual unsynchronized: The maniacal laughter just before the credit rolls does not match the mouth of the laugher.