When the inspectors get Silien in their car, the background starts sliding prematurely as the driver hops in, albeit the engine was not running.
When the first murder takes place, a lamp on a long cord is knocked from a table. In the next shot, it's swinging in a different direction than it did when it fell, and much more vigorously than it would have been possible.
When Fougel frantically drives in heavy rain to Silien's home, exterior shots of the car show the rain running straight down the door and window, instead of flowing backwards with the wind.
In the night club, the trombonist's slide movements don't match the music on the sound track.