The pulsating music and lighting makes The Stinger of Winnie the Pooh (2011) somewhat unnerving. Of course, once the Backson starts talking, it switches to funny.
In The Tigger Movie, the avalanche scene and how close Tigger got to being killed in it. Granted he didn't, but still.
The Bad Future dream sequence of Winnie the Pooh: Springtime with Roo, where it's revealed that if Rabbit keeps up his Control Freak tendencies, the others will finally give up and leave the Hundred Acre Wood, reducing it to a desolate, creepy area with all it's foliage dying. The real clincher is when Rabbit begs the narrator if he can change the words of the book, and for a moment it looks like it's too late, since he has lost the belongings of his friends to make amends with them, and the words seem to have been already written.
In the now-infamous "Too Smart for Strangers" episode of Welcome to Pooh Corner that's the Trope Namer for Too Smart for Strangers, Pooh says that you should be suspicious of anyone you don't know, stay away from secluded areas, and to run away if you "meet a stranger" which is hard to avoid doing in populated areas.
