ANH: "prisoner transfer from cell block 1138"
ESB: "send rogues 10 and 11 to section 38"
ROTJ: i'm told that 1138 appears in the stars at the end battle. but i've never seen it myself.
TPM: 1138 is the number of a battle droid (end battle, droid ship goes critical, and the 1138 droid turns off right in front of jar jar)
AOTC: when Padme falls out of the transport and rolls on the sand she leaves a 1138 in the sand.
and there are a couple of '1138's on clone trooper helmets
ROTS:
spoiler: commander 1138 is one of the clone troopers that is ordered to turn on the jedi
i'll let Astro carry on asking questions seeing as he's so good at it.