Audio problem: When Max and the taxi driver start fighting, the taxi driver misses an audible punch by several inches.
Visible crew/equipment: When Max and 99 are trapped in the room with the hatch that leads down to the Guru's chamber, the filmmakers didn't bother to make it seem like a giant hole in the ground, and they also didn't bother about the floor of the set being about ten centimetres below the hatch.