Yiddish?

Yiddish and German have many similarities

http://en.wikipedia.org/wiki/Yiddish_language

"Yiddish (ייִדיש yidish or אידיש idish, literally "Jewish") is a High German language of Ashkenazi Jewish origin, spoken throughout the world. It developed as a fusion of German dialects with Hebrew, Aramaic, Slavic languages and traces of Romance languages.[2][3] It is written in the Hebrew alphabet.

The language originated in the Ashkenazi culture that developed from about the 10th century in the Rhineland and then spread to Central and Eastern Europe and eventually to other continents. In the earliest surviving references to it, the language is called לשון־אַשכּנז (loshn-ashkenaz = "language of Ashkenaz") and טײַטש (taytsh, a variant of tiutsch, the contemporary name for the language otherwise spoken in the region of origin, now called Middle High German; compare the modern New High German Deutsch). In common usage, the language is called מאַמע־לשון (mame-loshn, literally "mother tongue"), distinguishing it from biblical Hebrew and Aramaic, which are collectively termed לשון־קודש (loshn-koydesh, "holy tongue"). The term "Yiddish" did not become the most frequently used designation in the literature of the language until the 18th century.

For a significant portion of its history, Yiddish was the primary spoken language of the Ashkenazi Jews and once spanned a broad dialect continuum from Western Yiddish to three major groups within Eastern Yiddish, namely Litvish, Poylish and Ukrainish. Eastern and Western Yiddish are most markedly distinguished by the extensive inclusion of words of Slavic origin in the Eastern dialects. While Western Yiddish has few remaining speakers, Eastern dialects remain in wide use."

Yiddish is a dialect of German spoken primarily by those of Jewish heritage. Though, in the film that was pretty much hochdeutsch.