Goofs

The bottle shatters completely over the head of a Santa victim, yet in the next shot the killer has literally half of a broken bottle to stab the Santa in the eye.

Before another fake Santa Claus is killed, we see the gun pointing at the camera and not the victim. As the gun goes off, we see that the gun is now in the victim's mouth .

The blood on the upside down nude cadaver of an employee in the dungeon scene.

When Kate attempts to answer the telephone, she's strangled by the killer and grasps onto the phone while it's still on the hook; yet in the next scene Powell is able to answer Kate, even though the phone is still hung up.

The spilled presents in the flashback scene change position.

The title card reads "DONT OPEN TILL CHRISTMAS", missing the apostrophe in "don't".

A fake Santa Claus has his occipital lobe blown out; there's minimal blood spattered on the wall behind the victim, when there would've been a whole lot more.

As stated by Ian Harris, Sharon was attacked by the killer - when in actuality, she was more-or-less in a physical coercion (threatened at knifepoint).

The blood used in the film looks more bright red rather than a traditional dark red color when deoxygenated.

As Chief Inspector Ian Harris leaves the New Scotland Yard, his shadow passes over the sign revealing that an obvious stage light was used for the scene.

When the inspector visits Kate's apartment to discuss the attack on Sharon, Kate asks what happened, but her mouth does not move.

When one of the fake Santas' has a bottle smashed over his head, there's no sound to accompany it.

(At around 2 mins) In the beginning, a young couple have sex in their car; after the man gets stabbed - as the prologue is played out in killer's point-of-view - the killer shifts around the car and the camera, used to film the scene, is momentarily reflected on the driver's window.

After one of the doomed Santa Claus' stumbles upon the employee's nude and bloodied cadaver, the camera's silhouette can be seen on him.

One of the fake Santa stumbles inside the London Dungeon; before he turns around and winces at the adjacent guillotine, the camera's shadow can be briefly seen.

Lack of exposition for the killer and murders.