When Antoine and René go to the cinema, René wears a black coat, but in one shot he is wearing just a jacket.
(at around 59 mins) When the two boys run in the Sacre Coeur's stairs where they mock a priest, René's jacket changed. It's now longer and black. And just after when they come back to his house, he again is wearing the first jacket.
(at around 1h 00 mins) There is a visible film splice that occurs when the cat sitting on top of the bookshelf in René's home comes into view and instantly shifts position, just before René moves the hand of the clock forward.
When René comes to visit, the position of Antoine's hands on the door changes.
(at around 1h 28 mins) When Antoine is standing alone against the wall, there is a visible film splice that occurs just before he looks up after taking a bite of food from the bowl he's holding.
(at around 1h 39 mins) At the end, right as Antoine reaches the water's edge, the shadows of the crew can be seen on the sand and water.
When Antoine is looking in the mirror and his father is behind him, the camera can be seen reflected in the mirror.
(at around 24 mins) At the end of the gravity wheel sequence, the camera pans up to look at the crowd which reveals the boom mic in the center of the screen.
(at around 1h 22 mins) When Antoine is being fingerprinted, the officer rolls his fingers back and forth on the fingerprint card. This is incorrect, as it will result in a blurred print. Prints are taken by carefully rolling the finger from one side to the other only once to ensure a clear print is obtained.