A search for copyright renewal was done at copyright.gov using the film title. Only one listing was located-for the book on which the film was based:
Type of Work: Text
Registration Number / Date: RE0000397731 / 1988-10-14
Renewal registration for: A00000436177 / 1960-01-26
Title: Yellowleg. By Albert S. Fleischman.
Copyright Claimant: Albert S. Fleischman (A)
Variant title: Yellowleg
Other Title: The Deadly companions.
There's no evidence of continuing copyright for the film or material related to it.
Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.