(at around 14 mins) In Puppet Master (1989) it is stated that Andre Toulon killed himself in 1939. However, when Patrick finds his grave in the cemetary, it says he died in 1941. This does, however, fit in with the altered continuity as related in Puppet Master III: Toulon's Revenge (1991).
(at around 1h 13 mins) When Andre Toulon is explaining everything to Carolyn, the male dummy has white gloves on, but when Andre is doing the spell, the gloves are gone and remain gone.
(at around 1h 23 mins) At the end of the movie when Elsa pulls over her van to the side of the road, she states they should have taken a left back at the crossroads. But when she starts back up she continues to go in the same direction without turning around to go back to the crossroads.
(at around 54 mins) When Andre Toulon goes to his room and sees the puppets Pinhead and Blade working on the formula all by themselves, strings are visible moving Blade's arms.
(at around 1h 11 mins) When the puppet Torch comes into the bedroom and sets the bed ablaze where Michael is, in the next shot you can hear the fire extinguishers putting out the fire.
(at around 2 mins) At the beginning of the film, when the puppets bring back Andre Toulon, and you see his undead corpse rise from the pit, when the thunder strikes you can see two strings pulling up his skeletal hands from the grave.
(at around 14 mins) The cemetery outside the hotel is misspelled 'ceme ary" (the 't' is missing from the sign).
(at around 1h 21 mins) Towards the end of the movie when the Jester Puppet takes something to Camille, a crew member's hand is visible for several seconds holding and walking the puppet through the brief scene.
(at around 1h 7 mins) When Wanda comes into the room and Blade comes after her. A lamp drops when she knocks the table, but before it completely falls off, a hand can be seen grabbing it.
(at around 33 mins) When Blade and Leech Woman go to kill Martha and Matthew, you can see a stick help move Leech Woman across the floor when she's entering the house.