I've been reading the forums a lot, reading all the theories and things people may have which could contribute to this entire thing, but one thing I haven't seen is this.
"I found something:
The jetpack could be in the tunnel,
The egg is the Cluckin Bell factory,
The UFO is the restaurant with an rocket outside. The rocket makes weird cracking sounds and sometimes it beeps.
Maybe there is a tunnel from the restaurant to the closed tunnel?
Maybe there is a way to open this door behind the rocket restaurant."
This interested me a lot, I'm not sure if this has been brought up but it's certainly interesting.