Reginald VelJohnson as Stallings, with Darius McCrary as Rawlins. VJ doesn't match Stallings exactly, and McCrary might be smaller than Rawlins is supposed to be. But it's pretty much mandatory that VJ play a cop.
Also, for the record, William Hootkins (RIP) as Eckardt from Batman is the definitive Carmichael.
Since he's no longer available, I'd settle for Jason Alexander doing an impression.
On a random tangent, Nikolaj Coster-Waldau as Vadderung. He's younger than most candidates, but I feel like a little gray hair and makeup will allow him to fit it nicely. He's got a wolfish look, and his cocksure grin is very Odin-like.