Goofs

After Isabelle sets the table for Christmas dinner, the dinner plates change positions.

When Albert carries the tar paper out on the roof, he is seen putting it down twice.

The plates that Albert has thrown haphazardly on the Christmas dinner table change positions in the next medium shot.

When Andre is talking to Felix and Joseph, his left arm is stretched. In the next shot, it is folded and leaned on his hip.

A piece of straw pops into Joseph's mouth without him touching it as the three escapees lounge on the dock.

After Jules makes Paul to enter in the Uncle Andre's bedroom, he takes the gramophone amplifier and makes a sound with it to announce to his friends that the body will be found, then puts it on the table upside down. Later in the film, the gramophone appears perfectly tidied.

However, Amelie Ducotel later followed Joseph, Albert, and Jules out of the sun room. It's likely she replaced the gramophone amplifier to its proper place.

(at around 1h 5 mins) Paul leans over to turn up the bedside lamp, but the light starts to get brighter before his hand reaches it.

The movie supposedly plays on Devil's Island (It's superimposed in the establishing shot at the very beginning.) and Ducotel's general store is located in Cayenne (It's mentioned several times.), the capital of French Guiana. However, Devil's Island exclusively was a penal colony with no civilian settlement, and Cayenne lies on the mainland coast, approximately 50 miles east of Kourou, the closest mainland town to Devil's Island.