Kenny kills Ben and the group loses their boat according to the ign video review, though this is probably if you left no one to watch it.
With Kenny killing Ben, it's probably if you left them two alone at the boat.
It also seems that the cutting off of Lee's hand is indeed a possible outcome as Christa attempts to cut it off.
And based on the review, it seems like they temporarily return to the house possibly in the beginning of the game.
Anything else people want to point out?
The video is on top and should be working now.