1. Possible sequel. As of now, Tarantino has pretty much filmed all of the crackpot projects he has ever announced over the years, with the exception of two Elmore Leonard novels (Freaky Deaky and Bandits) and his prequel The Vega Brothers, which would "reunite" Michael Madsen's Vic Vega (from Reservoir Dogs) and John Travolta's Vincent Vega (from Pulp Fiction). In reality, it doesn't look like any of those things is going to happen, but actor Omar Doom revealed that Tarantino has some "500 leftover pages" from Basterds, and could very well do a prequel explaining the origin of Aldo Raine and his group. I'd see that, just to hear Brad Pitt pronounce the word "Nah-zees" again.
2. The Three Fingers Thing. In one scene, an undercover spy gives himself away by ordering three drinks and holding up the wrong three fingers. Tarantino says, "that was actually a thing" and remains so to this day. He remarks that WWII was the last time that a bunch of white guys fought against a bunch of other white guys, and so one group could actually infiltrate the other, if you could pull off the accents. And the finger thing.
3. Mood Music. Tarantino is famous for listening to pop music while writing, and sometimes his music of choice makes it into the final film. Thankfully, this time he was working on a period piece because the song that he repeated most was, apparently, "I'm Yours" by Jason Mraz. Um, my wife loves that song, so... no further comment.
4. Bad Dreams. During shooting, B.J. Novak, who also stars in TV's "The Office," apparently had some very weird dreams about his co-star Steve Carell and guns. Gives a double-meaning to the word "shooting."
5. Projectionist in Training. Don't think Tarantino was going to let French actress Melanie Laurent, who plays the Paris theater owner Shosanna Dreyfus, onto the set without her knowing how to run a projector. One night, he put her on a three-hour crash course, making her show Reservoir Dogs, plus a bunch of cartoons and trailers, doing all the reel changes by herself. Good thing there was nothing flammable with her in the booth.