A watch button plays a different film, or the poster/plot doesn't match.
Movie details (posters, plots, cast, ratings) come from TMDb, and links come from YouTube — occasionally a source gets matched to the wrong film, especially for remakes and same-title films in different languages.
1If a watch button plays the wrong film, report that source from the movie page — mismatches are treated like broken links.
2If only the details look off (say, the poster from a different year's remake), a report on the source still gets it reviewed.