Why yes, they ARE holding hands.
The Defiant Ones was an awesome, awesome film starring Sidney Poitier and Tony Curtis as convicts who escape from a chain gang - chained together. I've recced it before, even, except now I have screencaps!!!
Joe has sacrificed his (very good) chance at escape in order to save Cullen, getting himself shot in the process. Cullen then sacrifices HIS chance at escape because he won't leave Joe behind.
Don't worry, it's just a flesh wound *g*
"You'll make someone a fine old lady one day."
"I guess I will."
Cullen is looking up at the Sheriff standing over them with a gun. Joe's more interested in looking at Cullen. D'Aw.