In the episode adaptation, the original mask is shown to be fully sentient and has complete control over its host when it possesses the shopkeeper. Compare this to the original book/episode, where it's barely a character and gradually corrupts Carly-Beth into berserk rages. This could be chalked up as inconsistency, but given this thing is a living organism that bonds physically and mentally with its host, the mask may have used its acquired knowledge to grow in power and intelligence.
In the original TV episode, Sabrina wore a rather amateurish-looking cat costume and was mistaken for a “giant hamster” by a young boy. This might be why she didn’t wear the cat costume in the sequel, instead dressing as a (more realistic) tiger. Hilariously, though, the exact same thing happens anyway when an old man mistakes her for a cat instead of a tiger.
Steve's new mask transforming him into an old man is related to a character flaw, just like the first book. Carly Beth wanted to be feared and got a mask that turned her into a vengeful monster. Steve spends the first half of the book beefing with a bunch of rowdy first graders who won't respect him as their elder. He becomes the extreme of that: a decrepit old geezer who gets the respect of the kids at the cost of his youth. Now, what is the title of that other book about wishes...?
Since the old man mask rapidly aged Steve, there's a good chance he could've been sentenced to an early death if he hadn't been able to get it off.
The TV version implies that the supernatural forces surrounding Halloween are what bring the masks to life. If the masks were all destroyed (save for the main one, which seems indestructible), what's to stop these same sinister entities from possessing children through something else?
The plaster head of Carly Beth gets smashed by Steve in this episode, right after it asked him for help. It appears to have been partly sentient independently of the mask’s magic, since we see it smiling before Carly Beth even visited the store with the mask. And then it just got unceremoniously smashed, although Steve didn’t really have a choice.
