Quentin Tarantino gave an interview to the LA Times, in which he discusses the films that influenced Inglourious Basterds, although he first expresses annoyance with critics who, instead of reviewing his movies, really try to “match wits” with him, and try “to show off every reference they can find, even when half of it is all of their own making.”
Of World War II films, he says: “They were fun and thrilling and exciting and, most amazingly, they had a lot of comedy in them, which really made an impact on me. I mean, for every movie with a sadistic Nazi, there’s one with a Nazi who’s more of a buffoon or a figure of ridicule.”
More details here, including how he prepared each of his actors with a special screening series.