As Hugo leads Max & 99 to their room, Drago is seen sitting then laying down in his coffin. However, when he catches Max & 99 investigating, the coffin has a staircase inside which would have made laying down uncomfortable if not impossible.
In the scene in front of Drago's, Control's Science Chief steps out of his car and it is undamaged. Later, in conversation with Agent 86, he says that he knew Smart was following him when Smart rammed the rear end of his car.
During the lightning strikes as Max and 99 get out of their car in front of Drago's castle, the top edge of the scrim and the back wall of the sound stage are briefly visible.
Dr. Drago says at high "C" the ice pellets fire. However, the note playing when the ice pellets fire when agent 52 dies is not a C, it is an A-flat.