20 Things You Somehow Missed In Kill Bill Volume 1
8. O-Ren's Father Was A Sergeant Major In The U.S. Army
During the anime sequence, the Bride's narration informs us that she was born at a U.S. Army base in Japan, though doesn't provide any wider context as to those circumstances.
If you pay attention during the scene of her father's murder, though, we're given occasional glimpses of a badge on his Army uniform, which seems to indicate he held the rank of Sergeant Major in the U.S. Army.
It's incredibly easy to gloss over all of this, but given that O-Ren's heritage provides an obstacle to her ascendancy in the Tokyo criminal underworld, it certainly provides worthwhile context to both her personal and "professional" life.