I went back and reread this, and now I’m going to add Shea Whigham as Officer O’Hara, the cop who keeps trying to tell Mortimer about the (increasingly weird-sounding) script he’s working on for a stage play; and, having seen him as Dr. Frost in Carol’s Second Act, Kyle MacLachlan as the head of the Happydale Sanitorium— he does “affably clueless” rather well, and Christopher Walken, the other actor I thought of, is still a bit too sinister.