Unlike most of the other period cars shown, Fritz Bauer's official, chauffeured Opel Kapitän does not have an official registration seal on its rear license plate through the entire movie.
Fritz Bauer is shown checking into the American colony hotel to meet the Mossad. In 1957, that hotel was under Jordanian rule, and totally inaccessible to Israelis.
The 9mm-round Bauer is sent in the mail has a Norinco headstamp, dated 1992. Norinco was founded in 1980, and a round dated 1992 would obviously not exist in the late 1950s, when the scene takes place.