Comment by dredmorbius

This happens more than you might expect.

There are several films which became popular staples on television after copyright expired, wasn't renewed, or was improperly registered in the first place (prior to automatic copyright assignment enacted in 1976). It's a Wonderful Life is the canonical example, though there is a long list of other public domain films in the US: <https://en.wikipedia.org/wiki/Berne_Convention#Adoption_and_...>