Jayvee Enaguas (HarvettFox96) reviewed the copyright for the animated short film on November 28, 2021, which includes most materials and elements.
At the opening title card sequence, it has a copyright notice that reads "Copyright MCMXLIII by The Vitaphone Corp. All rights reserved."
Vitaphone didn’t file a registration entry of the animated short film in the original print throughout 1943 and 1944, and later in the (current) Blue Ribbon reissue print throughout 1950 (1, 2) and 1951 (1, 2).
United Artists (who acquired Associated Artists Productions library containing pre-August 1948 titles in 1958) didn’t file a renewal entry of the animated short film for the original copyright within a required 28-year period throughout 1970 (1, 2) and 1971 (1, 2).
Therefore, the animated short film automatically entered the public domain on the first day of January 1972.
The (current) Blue Ribbon reissue print altered opening and closing card sequences and removed the title card sequence from the original print.
The animated short film is freely available and distributable in both physical and digital formats.
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.