These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Fridge Brilliance: In an odd one from the They Just Didn't Care area, in the second film a flashback seems to set up that Toulon learned how to animate puppets there. But Retro changes this, but the brilliance comes from how that flashback was written. As in Retro Toulon animates the puppets by magic. The old man in II says calls his methods are of the old way. Meaning actually this was where he got the formula and not just the start to making his living puppets.
Narm Charm: A part of why it has so many sequels... the cheesy effects and cheesier acting are just too endearing to hate.
Nausea Fuel: Anything involving Leech Woman. The first movie cements how disgusting her power is.
Special Effects Failure: The quality, and look, of the puppets in the movies after 5 take a nosedive as the series progresses.
In one scene of Retro Puppet Master, you can hear the servo motors coming from the puppets.
They Just Didn't Care: Puppet Master: The Legacy is 9 minutes of new footage adrift in 62 minutes of stock footage that sloppily tries to connect all the movies in one continuity.
This is especially true about the dates. If you want to you can fan theory all the plot parts to get everything where they need be, but there's squat way to recalibrate a straight timeline by date.