In one scene, a man and a woman are having sex and her bare breasts are visible. However, in one facial shot of the man during the same sequence, we can see her reflection in his sunglasses and she is clearly wearing a bra.
When Flavia removes her jewellery and lies naked on the bed, Fabio can be seen walking towards her in the mirror. In the next shot he is still sitting at the table and then walks towards the bed and the scene cuts back to he previous scene where he was seen walking in the mirror.
When Marco is shown after slapping Marzia, there is no glass with drink in his hands he took not a minute ago.
It is said at the beginning of the movie that crime happened in the evening, but in the flashback scene it's clearly not evening.
Flavia obviously moving her eyelashes and breathing at the start of the movie even though she is supposed to be dead.
Inspector says Caron shot at the guard, but he didn't.
Flavia isn't in the water long enough to have swallowed enough water to drown.