Marshall, by way of a Stable Time Loop, is the source of all weirdness in EerieBear with me on this 'cuz it's a long one. In the Lost Hour, two things are very strongly hinted at. One: Marshall is the milkman in the Lost Hour. Two. The milkman still exists outside of the Lost Hour (as shown by the milkman driving away from the milk bottles on the doorstep at the very end of the episode). This suggests either that, in the future, Marshall goes back in time AND gets caught in the Lost Hour again, perhaps intentionally to guide his younger self, or that, due to the Lost Hour's position outside the normal flow of time, it's possible for the milkman to exist at any point in normal time he desires, as he still ages and then goes back to the Lost Hour, but not traveling backward in time to be there at the right moment. And if Marshall exists as the milkman in Eerie in all points in time, then this provides shocking revelations about the nature of Eerie itself. What hit and killed Trip in 1929 before his letter could be delivered? The milk truck. What hit and killed Devon, allowing his heart to be transplanted into Melanie, Marshall's first love, allowing her to stay alive and share their first kiss? The milk truck. What is the impetus of Marshall, Simon and the cop confronting Todd's dad about his abusive behavior and allows the two to bond? Todd steals and crashes the unattended milk truck. The theory is this. Eerie really is as boring as it appears to be but Milkman!Marshall causes the events to happen to provide his younger self with a fascinating childhood. He hits and kills two children, knowing how they'll affect his younger self; he leaves his milk truck unattended when it's most important and he probably had his hand in other things behind the scenes. Due to the presence of some kind of stable time loop, by being the Milkman and creating the weirdness, the weirdness exists for him to become the Milkman in the first place. This also explains why Marshall seems to be the only one aside from Simon and Dash that realize anything is weird in Eerie. All the weirdness is centralized around him specifically because it's tailor-made for him.
Eerie is in close approximation to Indianapolis, IndianaOr more specifically, a suburb (i.e. Fishers, Caramel, etc.), considering it's population size and its building sizes. Another hint/clue is when a dog from The Retainer says "Eerie today, Indianapolis tomorrow!" Though it is just a figure of speech, it makes sense literally as well.
"Reality Takes a Holiday" was the mid-season retool incarnate.Think about the Re Tool: As soon as he arrived, Dash X started to pull focus, Fonzie style — a cool, new kid with a bad-attitude and a mysterious past. Why add a character like that when the show was supposed to be about Marshall and Simon dealing with the weirdness of Eerie? One possible answer is maybe someone on high thought the show was ripe for cancellation and handed down notes on what to change to save it. And maybe someone thought the show would be better if it was about Dash instead of Marshall. Now look at the series finale again: Marshall finds out his life is a TV show and he's the star, but another guy is about to take his place with the network's blessing. In other words, it's a retool. The last time we saw Dash, he was alone in the world, relatively powerless and searching for answers about his identity. He was scheming and selfish, but he had a conscience and could be counted on to help Marshall out in life-or-death situations. Now he's being treated like a star and has seemingly managed to bamboozle an entire network into making him the main event, something he's willing to murder Marshall to keep. No hint of guilt or even responsibility from Dash. He seems to only know who he is and what he's capable of once he's aware he's a fictional character. When Marshall runs off, Schaefer makes it clear that if the show doesn't go on, they're cancelled. So Marshall's life and Dash's plan aren't the only things at stake here — the show is over if Dash doesn't win.... And he doesn't. The take-over plan is a bust and Eerie, Indiana is canceled for good. But the show ends on a high note: Marshall is still the star and the show doesn't care if he's doing something "uncool" like going to the movies with his family.