You’re completely correct. But they spent a ton of time building it up.

My theory is it is either what Reginald said, a magical time and space machine. Or, it’s Reginald’s original ship that he escaped on. And he has to get back in there and manipulate things.

Since the MacGuffin machine runs on Marigold particles, and marigold particles were created by Reginald’s wife, I think it makes the most sense that the MacGuffin machine is Reginald ship . Not to mention the hotel he created was a mirror image of the ship interior, and he created that hotel before he could see the ship. So that tells me he knew what he was looking for.

Now why does Reginald ship have a security system that Reginald can’t control? Not sure, we could come up with a bunch of reasons. But it’s interesting