Situation in Germany
It is not forbidden to show Nazi symbols in movies. They are shown regularly and not edited out. They are also used in local productions.
The situation was different a few decades ago. Jurisdiction had a stricter approach to the legal situation and assumed that any depiction of Nazi symbols was illegal. This lead to cuts, blurs, or edits. E.g. the computer game Indiana Jones and the Last Crusade was edited and depicted iron crosses instead of swastikas (a quite common approach). The computer game Wolfenstein 3D was put on the index 1994 for showing Nazi symbols (and not for the depiction of violence). The Star Trek TOS episode Patterns of Force premiered on German Free TV just in 2011 for the same reason, it wasn't shown when the series ran for the first time. This is not the current state of interpretation of the legal basis.
The legal reason is § 86a StGB (Article 86a of the penal code)
Verwenden von Kennzeichen verfassungsfeindlicher Organisationen (Usage of symbols of unconstitutional organisations) in combination with Artikel 5 des Grundgesetzes (Article 5 of the constitution). The constitution allows free speech, explicitly including images (paragraph 1). As with every right there are borders (paragraph 2), namely common laws, laws for protecting the youth, and the right of personal honour. Paragraph 3 names some exceptions to the borders (Schranken-Schranken, border-borders) in paragraph 2, namely for art and science.
§86 forbids the public usage, production, storage, import, and export of symbols of certain unconstitutional organisations. Those are specifically most former Nazi organisations plus some Neo-Nazi organisations. It includes symbols, uniforms, flags, greetings, phrases and more.
§86 StGB defines an obvious border in the meaning of Artikel 5 paragraph 2 GG.
The main legal discussion was whether movies and TV episodes are "art" in the meaning of Artikel 5 paragraph 3 GG. For decades they were seen as "trivial entertainment" and not art so not eligible for the border-border in paragraph 3. Today the definition of art is more lenient so the exception in paragraph 3 applies to them, movies and TV episodes can depict Nazi symbolism. Of course this doesn't apply for works of propaganda which are disguised as art. There are some works where the state is dubious but that is not a common problem. So works like Operation Walküre (with Tom Cruise) can display Nazi symbolism even when shown in Germany today.