Between 10 to 15 minutes into the movie, Tigger and Roo visit Owl. At a certain moment, Tigger empties the sugar pot in his cup of tea to make it tastier. A little bit later, when Tigger shakes hands with Owl to thank him, all the sugar has gone back from the cup to the sugar pot.
During the family reunion scene as Piglet bounces on the chair, his jumper is missing it's stripes.
Tigger arranges Owl's family portraits to resemble an actual "family tree". However, the portraits are later hung back to the way they originally were.
The doorknob on Tigger's front door changes sizes between shots during the family reunion scene.
When Eeyore sinks into the pond where the striped frogs are and says "Not that anyone will miss me", his voice doesn't sound gurgled.
At the end of the movie when everyone is getting their picture taken for the locket, Roo rests one arm on Tigger's arm and his other arm is at his side, but in the photo, Roo is holding Tigger's arm with both hands.
During the opening sequence, the book on Christopher Robin's dresser opens to reveal the "Winnie-the-Pooh" title. However, when Tigger pops in front of the camera in outrage during the same shot, the book noticeably changes its position as he does so.
The movie starts with narration by John Hurt that helps explain the nature of the Hundred Acre Wood for any newcomers, before introducing Tigger and his goal to find his family tree. But as the movie drifts off into Roo's "big brother" worship towards Tigger, the narrator doesn't come back at the end, and the characters are on their own in the long run.