(First off, apologies if this is the wrong subforum/etc., I haven't used the forums much before)
When invited to someone else's orbiter, the guest can 'hijack' some host interactions. Discovered this by accident with a buddy when I went to pet his kubrow, and it put him in the animation instead.
More critically, though, is the fact that the guest can put the host into operator mode, even if the host hasn't completed the second dream. He was able to walk around the transference room, and even interact with the chair, customize his appearance, and mess with focus. I tried to play it off so hopefully it won't be completely ruined for him once he does get there (and I'm definitely rebinding my ability key that I hit on accident while I was trying to leave), but hopefully this can be fixed before anyone else gets spoiled by it.
I'm not sure what other interactions are affected, but I can say for sure interacting with the host's pet and hitting the ability key (probably also 5) will affect the host rather than the guest.