Hahahaha. I read your post and looked at the thumb and didn't really pick up on the illusion in the thumb. The full size image just had me laughing... I guess the first thought I had of the floating head was that's Will Farrell eyeing the kid's drink and this is some kind of Saturday Night Live skit.... Just my weird imagination I guess.
The floating head guy! The others are not exactly sure they want to be witness to the event, so they're not watching. In reality, the only watchers are the plants, and you'll notice they're paying VERY close attention to both the bodyless guy, and the strolling teens. I think the teens are gonna be history....