Game Theory Undertale

I'm sorry, but this is the first theory that I actually don't agree with. There are quite a lot of holes in here:
-Sans states that they made the costume a few months back for a costume party
-If the people on the picture are Ness and his friends, how could Frisk recognize him?
-The "strange symbols" on the blue prints are most likely Windings and thus written by Gaster.
-The whole "Trying to go back" thing during Genocide Run is most likely referring to time travel, I don't know what he's talking about when you grab dinner with him at the MTT Resort, though (probably something to do with time travel as well).
-"and getting back to the surface doesn't really appeal, either" That's not saying that he no longer considers the surface his home, the next line explains that "cause even if we do... we'll just end up right back here, without any memory of it, right?" This is of course referring to all of the resets the player makes.
-The strange machine is probably a time machine.
-I am 90% that the picture of the 3 smiling people that says "Don't forget" is of Alphys, Gaster, and Sans. People have speculated that it's Papyrus instead of Alphys but there is a special line of dialogue during the True Pacifist ending which implies that Sans and Alphys know each other. It's also implied (I know I say "implied" a lot here but you kinda have to when talking about Undertale lol) that Sans was a scientist once, and besides, it makes more sense than having Papyrus there, since we can assume that Alphys and Sans were Gaster's lab assistants or something like that (Unless you're one of the people who thinks that Gaster is Sans & Papyrus's dad but I'm not getting into that).
-Sans isn't the only one who knows about the sun. Alphys says something among the lines "It's even better than on T.V!" regarding it.
I am honestly rather disappointed with this theory. In my opinion, you can't really make a Sans theory without talking about Gaster. Even then, I expected something better than "WHAT IF SANS IS NESS?!" Still, it was an alright video, hopefully you'll make something regarding Gaster in the future.
Oh and P.S. it's called "The Underground" not "Underworld."