The Hangover/Fridge

Fridge Brilliance

 * What happened with Stu & Jade starting a relationship at the end of the first film? Simple, he mentions at the start of the sequel that he's still seeing a therapist to cope with the events of the first film. Stu simply couldn't date Jade because she & Tyler were reminders of what happened in Vegas.

Fridge Horror

 * What if they'd found Doug straight away & left without resolving the issue of the tiger in the bathroom? What if they never found the baby either?
 * Jade does have a key, and was only out of the room a few minutes to get coffee. She would have taken her baby if they had left him there. The tiger was locked in the bathroom and so wouldn't have been able to eat the child. If they had left the tiger there, one can assume the hotel would have called animal control and it would eventually be returned to Mike Tyson (assuming it was legal for him to own it in the first place).