What is the penalty, if any, for mistakenly paying US federal taxes as US tax resident instead of a non-US tax resident?

Determining the US tax residency can be slightly tricky and as a result I wonder what the penalty is, if any, for mistakenly paying US federal taxes as US tax resident instead of a non-US tax resident.

Assume that paying US federal taxes as US tax resident doesn’t yield any money saving compared to filing as a non-US tax resident (i.e., no malicious intent, just an genuine mistake).