Mercury

Character mistake: After Ricky has just killed his girlfriend with the car antenna, he's challenged by a police officer. Officers would never walk right up to someone who have just committed a murder. Police would always order the suspect into a position that presents the least amount of threat and minimal chance of resistance. Grabbing the officer's gun would never had been an option.

Mercury

Continuity mistake: When the mother superior enters the kitchen to retrieve a knife to protect herself, there is a coffee mug on the bench in front of a white vase. When she turns around to exit the kitchen, the vase is visible, but there is now no coffee mug. Even at a different angle the mug should still be visible as well.

Mercury

Plot hole: The police are on the trail of a known psychotic and mass murderer. When they turn up at the house of the mother superior, it's evident Ricky has been there, as the door has been cut open and kicked in. There is no way the other nun would have been able to freely enter the house without police escort, or even get out of the police car, as Ricky had not been located and apprehended. The house is a potential crime scene and she would not have been allowed in.

Mercury

Continuity mistake: When Ricky and the mother superior are at the top of the stairs, in closeup Ricky raises the axe right up over his head ready to strike and he has one hand at the bottom of the handle and the other hand further up the handle. Cut to the next scene where the mother superior is ready to leap from her wheelchair, and Ricky is now suddenly backed into the corner. With no room for the axe to be behind him, his arms are no longer raised and his hands are now together, both at the bottom of the axe handle.

Mercury

Trivia: The house number of the strict, God-fearing mother superior is "666" - the number of the beast.

Mercury

Other mistake: When Ricky confronts the mother superior in the dining room, Ricky raises the axe above his head and brings it straight down in one single motion. Both Ricky and the mother superior are facing each other. At that angle, it would have been impossible for Ricky to decapitate her. At best her head would have been cleaved in half, but not decapitated.

Mercury

Continuity mistake: While Ricky is on his shooting spree, he manages to shoot at an oncoming car, causing it to to crash and roll over. As the car rights itself, the driver and the car seats are visible. The right rear passenger window is also fully intact. Just before the car explodes, the driver has disappeared, along with the car seats and the same rear side window is now completely missing.

Mercury