When Madeline's parents find her on the steps of the city, she turns around to her right to interact with Eeyore, and the next moment she is turned around to her left looking at him, then the right, then the left.
Pooh's voice echoes in the Hundred Acre Wood, but trees don't return an echo since their bark and leaves absorb most of the sonic energy - and what little sound is reflected goes out in all directions, rather than back to the original source.
At 1:17:20 Madeline's sidecar on her bicycle is on the wrong side for British roads. It should be kerbside (left) of the bicycle.
When Madeline thanks the policeman she says 'Thank you, officer'.
This is England in the late 40s and she should have addressed him as 'Constable'.
When Christopher Robin encounters Pooh at a bench in the park, American robins can be heard tweeting in the background.
Hartfield Station had one platform not two or three shown in the film.