Continuity mistake: At the beginning of the movie, you see that the baby Matilda's eyes are brown, but they change colour to blue when she's in the car.
Suggested correction: It was just the lighting. The sun was shining through the window in the morning.
Audio problem: When Zinnia combs back Harry's hair with the grey stuff in it, we see her lips moving, but we hear Michael's voice.
Suggested correction: At 00:34:00, Zinnie combs Harry's hair, and she says to him, "Come here. OK." It is 100% her voice that we hear, and not Michael's.
Revealing mistake: When Matilda telepathically makes the TV explode, you can see what looks like parts of an explosive hidden behind the screen.
Suggested correction: Clearly no sign of it.
Suggested correction: When the TV set explodes, it's a close-up of the screen and no device is seen. When it changes to a wider shot of the actual explosion, the glass breaks and some components of the TV set are shown. There is no way to distinguish between what is a component and what is, as you say, an explosive.
Suggested correction: There is no view of the explosive.
Visible crew/equipment: When Matilda makes the pitcher fly up in the air you can see the shadow of the stick that was later deleted and erased.
Suggested correction: Well, there was a pole attached to the bottom of the pitcher, which was used to make it levitate, and it was edited out in post. But there is no visible shadow of the pole in any of the shots.