Incorrect goof
"Arbeit Macht Frei" DOES appear over the entrance to Dachau. I have a pic of it.
shareIt appeared on many gates and entrances of those camps, but Dachau's version looks different than what was shown in the movie. I think the movie's version is actually from Auschwitz.
(Not sure, and can't be bothered to research it... just a quick glance at wikipedia and some other pages)