Hal tells the boys that their mother is coming home. Hal's hand on Dewey's shoulder/neck changes by camera shot.
Jorg (name on shirt) hands Gretchen's note to Francis who puts it in his shirt pocket. It changes position. First straight then tilted.
As Jorg hands Gretchen's note to Francis, the orientation of the note changes with the camera angle. The back of the envelope is towards the camera whether it is facing towards or away from Otto.
Francis puts Gretchen's note in his left shirt pocket. We see the folded shirt on the bed with the note in the right pocket.
At Malcolm's family's house in the pre-title sketch, the electrical power goes off. There is a comedic "Kerchunk" of (a) switch(es) being thrown. In reality we would not hear the switch.
When Dabney turns around during his birthing video to ask whether he can open presents, the television is clearly not turned on.