Luther also appears in 48 Hrs
From the weird coincidence department:
The Warriors, the 1979 now-cult classic about the gangs in New York directed by Walter Hill, has a character named Luther ... and that character was played by David Patrick Kelly.
48 Hrs., also has a character named Luther ... and he's played by the same actor, David Patrick Kelly. Walter Hill also directed this one.
That's not the coincidence, though. (Walter Hill and company certainly meant to use this as an inside joke, and there appears to be no link between the two Luthers -- although it's feasible.)
The coincidence is that right after I finished watching The Warriors the other night, I decided to watch something else. So I browsed through Amazon Prime ... and decided to watch 48 Hrs.
BOOM.