Tumblr doesn't let you respond to posts, so I'll do it here:

You discuss a comic in a recent Tumblr post. The scene with the snowglobe is actually a reference I think you missed. Specifically, the last episode of the 1980s-era TV show St. Elsewhere, in which it's suggested that the entire show took place in the imagination of a child whose parents say he is autistic.

From Wikipedia:

"The Last One"

The 1988 final episode of St. Elsewhere, known as "The Last One", ended in a context very different from every other episode of the series. As the camera pans away from the snow beginning to fall at St. Eligius hospital, the scene changes to Donald Westphall's autistic son Tommy, along with Daniel Auschlander in an apartment building. Westphall arrives home from a day's work, and wears clothes suggesting that he is a construction worker. "Auschlander" is revealed to be Donald's father, and thus Tommy's grandfather. Donald laments to his father, "I don't understand this autism. I talk to my boy, but...I'm not even sure if he ever hears me...Tommy's locked inside his own world. Staring at that toy all day long. What does he think about?" The toy is revealed to be a snow globe with a replica of St. Eligius hospital inside. Tommy shakes the snow globe, and is told by his father to come and wash his hands, after having left the snow globe on the family's television set.[1]

One of the more common interpretations[citation needed] of this scene is that as Tommy shakes the snow globe in the apartment, he also makes it snow at the "fictional" St. Eligius. His father and grandfather also seem to work at this hospital even though neither man has ever experienced such a role. By implication this interpretation suggests the total series of events in the series St. Elsewhere had been a product of Tommy Westphall's imagination.

This comic is applying the same conceit to Foster's Home For Imaginary Friends.