At the end of Waxwork (1988), Sarah leaves the burning building in a flowery dress. In this film she is shown leaving in a polka dot dress.
In Waxwork (1988), Sarah is from a wealthy family, and in this film she is dirt poor and living with a widowed alcoholic stepfather.
At the end of the original Waxwork (1988), which is supposed to be the same night as the opening sequence of the sequel, Sarah has short hair. In the sequel she has long flowing hair.
(at around 6 mins) The amount of mustard on Sarah's face after the 'hand' squirts it on her.
(at around 42 mins) "Gloria" raises her right arm, finger pointing to the door behind the couple. After the cutaway "Gloria" is lowering her left arm, then letting it drop limply to her side.
While the movie takes place in California, Mark makes several references to the possibility of Sarah receiving the electric chair. California has never used the electric chair as a method of execution.
(at around 5 mins) As the "hand" strangles the stepfather, you can see in one shot the hand is not on the man's neck, yet he still pretends to be choking.
(at around 1h 6 mins) Sarah, in Scarabis's castle, says that they are 700 years from the present day. Yet, George quotes Shakespeare, making it more like 500 years from the present day.
(at around 31 mins) When Sarah is on the spaceship she says that it's on "91" but that's not what her lips say.
(at around 46 mins) Roger says "Save the Bible", yet his lips clearly shape "Save the book". This redub was obviously done because the first object the possessed girl throws at Roger is a book.
(at around 5 mins) When the "hand" hits the stepfather with the hammer, you can see a black rod attached to the hand, controlling it.