Ewan McGregor did not know the name of the second prequel film of Star Wars during and after filming.

The statement is true. Ewan McGregor, who played the role of Obi-Wan Kenobi in the Star Wars prequel films, had initially stated in an interview that he didn't know the title of the second prequel film, "Attack of the Clones," during the filming process. He mentioned that George Lucas, the director, usually referred to it as "Film Two." After the completion of filming, he still couldn't recall the actual title accurately, referring to it as "The Attack of the Things" in another interview. This lack of knowledge about the specific title could be attributed to the fact that filmmakers often use working titles or different terms during production, and it is not uncommon for actors to have limited access to the final marketing decisions or titles of a film.