Hi,
Actually, Rick’s Barry should have dived into the ground instead of bouncing off. In later videos, you can see, that he doesn’t bounce anymore. Rick suspects that the surface effector made the head bounce in this case. Sometimes, there are undesired side-effects, and since we didn’t write the Collider2D classes or the surface effector class ourselves, we cannot prevent those side-effects. 
So, no, you probably did not do anything wrong.
Did this answer your question?
See also:
- Forum User Guides : How to mark a topic as solved