Finished it today. There's some really obscure secrets that are fun to figure out.
(Secret that is later on in the game)
(Secret that is later on in the game)
I found a room with a telescope. When I looked through it, I noticed two red dots in the top left of the screen. They blink in a pattern so I realized that they are probably a representation of what I have to hit on the bumpers. I did it and an artifact (I think?) appeared on top of the telescope. It doesn't appear in my inventory or give me an achievement so I have no idea what it is.