Continuity mistake: The first time Carly Beth takes off the mask, it falls to the floor, but suddenly jumps back up to her hands when she tosses to Noah.
The Girl Who Cried Monster - S1-E4
Other mistake: When we see Mr. Mortman transforming the second time, the shot is exactly the same as the first shot that was shown when he first transformed.
Welcome To Camp Nightmare (2) - S1-E6
Other mistake: At the end of the episode, Billy's parents tell him that they are taking him to a dangerous place called Earth and then direct his attention towards the sky where Earth is visible in high detail in broad daylight of the atmosphere of whatever planet they are on. If Earth is visible in such great detail, and at daytime no less, then there is no way Billy could not have already been familiar with it.
Suggested correction: The character is aware that the earth is in the sky, just not that he was being trained for a mission.
There's a difference between noticing an object in the sky and not being familiar with a prominent object in the sky. The show is implying that Billy knows nothing about Earth when his parents point it out to him and tell him it's "a place called Earth." This would be like someone on Earth seeing the Moon almost every night of their life and then not knowing any basic thing about it, including its name, until they were a teenager.
Night Of The Living Dummy II - S1-E10
Visible crew/equipment: In a wide shot of Slappy about to smash the guitar on the parents you can see that he is propped up on a stand.
Night Of The Living Dummy II - S1-E10
Continuity mistake: After Slappy's head is smashed off, the position of the broken face on the floor changes.
Night Of The Living Dummy II - S1-E10
Continuity mistake: When Amy's parents are talking to her while she eats breakfast, the whipped cream can sitting on the table moves between shots.
Continuity mistake: When Joey and Mickey are walking down the street and Greg and Bird see them, Bird says Mickey's last name as "Knotts" when addressing him. However, in the credit sequence, Mickey's name has been changed to "Ward".