No. This mouse, the Mouse of Minsk, was tall as a tree. His tail was a mile long. Really.
14 seconds sound clip from the An American Tail movie soundboard.
You can hear this line at 00:04:41 in the Blu-ray version of the movie.
Quote context
[...]
- It belonged to me, my father, and my father's father, and now, it belongs to you.
- Ah, did I ever tell you about the Giant Mouse of Minsk?
- No.
- Was it anything like the mouse with the long hair that the prince climbed up?
- No. This mouse, the Mouse of Minsk, was tall as a tree. His tail was a mile long. Really.
- He was so big, he frightened all the cats.
- Shh! Don't say that word. Talk about something else.
- America.
[...]