Other mistake: Near the end of the film when Jack-Jack is manifesting various abilities, his first display is of the human-torch-type of superpower. This would have burned away all of his clothing, yet (for obvious reasons) his diaper remains intact. This is particularly apparent as designer Edna Mode's costume for Jack-Jack was earlier shown as fire-resistant, but he was not dressed in his outfit during this scene.
Other mistake: When Helen is packing for the trip to find Bob, she is holding a outfit on a hanger. Watch how the coat moves when she slides it across the bed. Friction should cause the bottom of the coat to drag across the bed and while the top moves forward. Instead the bottom looks almost like something was pulling it ahead of the top. It give it a very unnatural look.