Revealing mistake: When MacPherson knocks Joshua off the platform, he falls on a bunch of pipes, but they are already bent before Joshua actually lands on them.
Continuity mistake: When Pete shows Artie the vial of Myka's blood, he is holding it between his first finger and thumb. When the shot changes to the front, he is holding it between thumb and ring finger.
Audio problem: In the second scene when Pete hits the sword wielding man with the shield, we hear the sound effect, but he misses by an incredible amount of distance.
Continuity mistake: When H. G. Wells tells the lawyer to step in the primordial ooze, just before he steps in his pants are already covered in it. (00:28:15)
