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.
