As originally suggested the in the Blades-Mad Match Preview the official was meant to be Mark Halsey until; late on Friday the official was changed to Mr. Riley.
The 1-0 defeat at the Boleyn Ground left the Blades stuck in the bottom three when the visitors should have gone away with at least a point after seeing a perfectly good goal disallowed near the end when keeper Robert Green was deemed to be fouled.
Warnock said: "I expected a free-kick. It was consistent with the rest of the game, which had a lot of free-kicks."
The former Bury boss slammed centre-defender Claude Davis and midfielder Mikele Leigertwood for their timely error which led to Hayden Mullins scoring the West Ham winner.
He said: "Claude has got to learn that Tony Adams, Rio Ferdinand and all the best centre-halves put it out of play when they have to.
"Then West Ham got a corner and I could tell from the bench that Mikele wasn't concentrating on his man."