Mr. Burns collapses on a sundial, pointing his arms at S and W - which to his eyes look like M and S - and identifying the initials of the shooter. This resulted in several characters having their names permanently expanded solely for the sake of red herrings: Seymour Skinner's name was revealed as M. Seymour Skinner - this is written on a diploma behind his head in one scene - while Moe the Bartender became Moe Szyslak, and Sideshow Mel's name was revealed as Melvin van Horn, presumably to eliminate him, though it could still have been interpreted as not MS, but SM - Sideshow Mel.
In Canada, due to a simulcasting glitch, the key moment where Mr. Burns is shot was interrupted due to a golf game running a few minutes late. Canwest Global had to re-air the episode again the following week.
This two-part episode makes two references to Dallas (1978). The entire "Who Shot Mr. Burns?" mystery is a parody of the "Who Shot J.R.?" mystery. At the beginning of this episode, Smithers has a dream in which he wakes up to find a completely healthy Mr. Burns taking a shower, and coming to the conclusion that it was all a dream, only to wake up again and find that it was not. Dallas (1978) pulled a similar stunt, in which an entire season, including the death of Bobby Ewing, was re-written as a dream of Pam's, with Pam awakening to find Bobby alive and well, taking a shower.