To credit the creator of subtitles, follow the MLA format template. If you substantively refer to or quote from the subtitles while discussing other aspects of the film, provide the name of the person who created the subtitles, if known, in the “Other contributors” slot:

Burge, Stuart, director. Othello. Performances by Laurence Olivier and Robert Lang, Japanese subtitles by Shunji Shimizu, BHE Films, 1965.

If your discussion focuses solely on the subtitles or you quote the subtitles without discussing other aspects of the film, provide the name of the person who provided the subtitles as the author of the subtitles. Then provide a description of the work the translator created (“Japanese subtitles”). Insert the name of the film as the title of the container, the director of the film as an “other” contributor, the name of the movie company as the publisher, and the date:

Shimizu, Shunji. Japanese subtitles. Othello, directed by Stuart Burge, BHE Films, 1965.