After Sue tries out the toy gun in the alley with the two innocent businessmen, the "four" logo on her uniform disappears, then returns when the angle changes.
As Reed Richards challenges Doom to a battle of wits, Thing appears to be standing in front of Reed, but is much too small in comparison. His animation cel was supposed to be layered behind Reed's shoulder instead.
When Reed Richards is challenging Doctor Doom, Doom's green cowl is colored brown by mistake.
Doctor Doom causes an all-encompassing power outage that shuts down every machine in the United States; but the Fantastic Four's computer, their hovercraft and their teammate, Herbie the robot, all remain unaffected.