When Gerald Ford and his staff watch Dreyfus' first TV broadcast, the television keeps changing channels between shots (watch the lit channel indicator panel).
In the final scene, where Clouseau, Cato and Olga crash through the wall, Peter Sellers' stunt double is only wearing a pair of white underpants. In the following high shot, where they fall into the river, he is enveloped in the leopard skin blanket from the bed.
In the first scene after the opening credits, Closeau gets off the elevator of the building where he lives. He is carrying groceries, and rice spills from a bags forming a big pile in the elevator. In subsequent shots, as Closeau opens the door to his flat and accidentally rips his pants, the pile of rice disappears. In the last shot, when he finally enters his apartment, the pile of rice is visible once more.
In the first sequence at the gay bar, Closeau and Ainsley Jarvis are talking. Bruno's macaw defecates on the right shoulder of Closeau's jacket. Bruno wipes the excrement, but it leaves a stain. Later in the scene, the stain disappears.
When Tournier climbs out of the train roof, he is in a toilet with a wall onto a hallway. When he is on top of the train, it has an "open-plan" layout, without hallways.
There is no power cord to the TV in the Oval Office when President Ford watches Dreyfus's broadcast.
All of the answers to the mathematical problems on the blackboard in Dreyfus's "schoolrooom" are incorrect. (Perhaps done on purpose by the film makers).
Dreyfus says that he will make the U.N. building disappear on October 9th at 3 PM Eastern Standard Time. October 9th falls during Daylight Savings Time.
At the beginning of the film, Dreyfus talks of rejoining the department after he is legally declared sane. This would be impossible as Dreyfus was found not guilty of murder by reason of insanity, which would legally prohibit him from returning to the police force.
The hospital sign is missing the French circumflex above the "o" in "hopital".
The sign for the psychiatric hospital at film's beginning is misspelled "Hopital," which is the French spelling.
After using the rake to pull Dreyfus out of the pond, it appears that Clouseau drops it on the ground with it's teeth pointing down. Watch closely, and you will see that he does indeed drop it with the teeth pointing up, so that Dreyfus steps on it and strikes himself with it.
After Clouseau pulls one of Dreyfus's teeth out, it is apparent that one of Herbert Lom's teeth is merely painted black.
At the end of the film, as the three characters plummet into the river, Clouseau is clearly played by a stunt double. Peter Sellers' hairy back, visible in the previous scene, is perfectly smooth.
The pile of rice in the elevator in the beginning of the movie is more than would've fit in the shopping bag.
During the "hovering Quasimodo" scene, while Clouseau is talking on the phone, shadows of the houses can be seen on the backdrop, which is meant to be the night sky.
When the television screen in Clouseau's apartment is pierced with a pole it appears to explode (although it not being switched on this would not happen anyway). In the next take there is no sign of any explosion- blackening to the set - only a hole in the screen.
After the UN building disappears, the officials rush into a room with a television, almost toppling on each other, to hear what Dreyfuss is saying. However, there was already a television set in the room they came from. In fact, they had just watched the UN building disappear on that television set.
When the US President is talking to an official about the number of assassins after Clouseau, the official informs him that "26 are dead, only the Russian and the Egyptian are left." However, there are actually three assassins left: The Egyptian (Omar Sharif) the Russian (Lesley-Anne Down) and a third man disguised as Clouseau himself, whom Sharif kills mistakenly. (Note: it was Drefuss' subordinate Tournier the bank robber who was disguised as Clouseau - who the authorities haven't seen since he escaped from the train - so was not recognized as being one of the designated assassins).
At the end when Dreyfus is hit by his own weapon he runs away when lower part of his feet are already gone and plays plays the organ when he no longer has hands.
During the scene in the men's room. When Clouseau steps out of the stall to retrieve the toilet paper and another man steps in. The man's feet are seen as if he is sitting on the toilet. But lowered pants are nowhere in sight. It clear the actor just sat down.
Clouseau hits himself with the vase and stumbles, causing a gun in the rack to fire. The sound of a bullet ricocheting is heard, but the doctor takes buckshot out of Quinlan's behind, indicating a straight shot.
The sound of the whoopee cushion is slightly delayed after Clouseau sits on it.
In one shot against the balcony during the "hovering Quasimodo" scene, the wires holding up Clouseau are visible.
During one point at the first fight between Clouseau and Cato, the camera's shadow is vaguely seen on Clouseau.
When Dreyfus makes the U.N. building disappear at 3 p.m. EST, it is broad daylight in Germany, where it should be 9 p.m.
When Clouseau sits on Inspector Quinlan's padded cushion and it emits a sound, Dudley Sutton is clearly seen trying to stop himself laughing.