The identities of look-alike actor brothers William Hudson (Attack of the 50 Foot Woman (1958)) and John Hudson (The Screaming Skull (1958)), real life twins, are frequently confused, even by B-movie buffs. Here, William impersonates John, who plays an LAPD detective.
When Malloy and Reed are on the way to Mrs. Burnside's, the pavement has been wet down even though the sidewalks are dry. This was done to even out the look of the pavement.
The owner of the gym is wearing a sweatshirt that says Rivers' Gym, but the sign on the outside says River's Gym, the apostrophe is in different places. Since the gym's owner's last name is Rivers, the sweatshirt is correct and the sign outside is incorrect.
Art Gilmore, William Boyett, James McEachin, and Virginia Gregg all made multiple appearances on the Robert A. Cinader/Jack Webb produced Emergency! (1972).
So named for the color of the capsules, "reds" is slang for secobarbital - better known by its brand name Seconal - a pharmaceutical barbiturate used as a sedative i.e. sleeping pill, but which recreationally is used as a hallucinogen.