Morrison, probably best known to American audiences as Jango "Father of Boba" Fett, will be playing Abin Sur. Abin Sur is a member of the Lantern Corps, and crashlands on Earth. In his dying moments, he searches for a worthy soul to be his replacement and wield the ring. The Ring chooses the young and cocky Hal Jordan as the successor. Obviously it's not a huge role this time around, but there's a possibility Abin Sur could return for sequels as the comics have him popping back to assist Jordan in various ghostly ways. It should also be interesting to see how they choose to portray the bald and red-skinned Abin Sur. Heat Vision is silent as to whether it will be motion capture or the old-fashioned technique known as "make-up."
Waititi's part is a lot less mythological, as he's merely playing "the best friend" of Jordan. I'm going to make a semi-educated guess and declare that he's playing Tom Kalmaku. Tom was an Alaskan Inuit, and given a rather racist nickname by Jordan's fellow pilots. Other than that wince-worthy moment, he's a pretty neat character as he's one of the only people in Jordan's life who knows of his Green Lantern gig. He's a good wingman. And who knows? Maybe we will see Waititi become one of the New Guardians in this age of crossover movies. Filming begins this week, so begin the countdown to costume photos!