That was despite the fact the Kenyan had his back to play and his arm was by his side.
Marius Zaliukas's shot initially struck the arm of Joe Ledley at point-blank range, then bounced up onto the hand of Wanyama.
The Hoops management team and players were already angry at the decision, and the ref's refusal to award them a spot kick a couple of minutes later when the ball appeared to strike Andy Webster in similar circumstances.
But after asking Norris about the controversial penalty, the Celtic camp were even more incensed to discover the match official was pointing the finger of blame at Wanyama.
Thompson confirmed: "He (the referee) has told the players after he has given it that it is Victor Wanyama."
Neil Lennon last night reiterated the mistaken identity allegation on his Twitter page. He tweeted: "Referee told players he thought Wanyama handled...feel so sorry for players and fans..I think it's personal myself."
The manager and Thompson, along with a handful of players, approached the referee on the pitch after the final whistle, and Lennon subsequently spoke to the match official in his dressing room.
Those conversations are expected to be included in the referee's report, and the Celtic manager could find himself the subject of yet another investigation by the SFA's Compliance Officer Vincent Lunny.
In Celtic's previous visit to Hampden in the League Cup Final, ref Willie Collum decided a challenge on Anthony Stokes in the dying minutes was not a penalty, but a dive by the Celtic striker.
Lennon described that decision as "criminal", and he will be asked to explain this comment when he appears before the SFA on Thursday.
On that day he will also be defending himself after his comments about the performance Calum Murray in the Old Firm game the week after the League Cup Final.
Lunny wrote to Lennon regarding a comment made about the referee before the game against St Johnstone on April 1, contrary to Clause 69 which forbids comment about officials in upcoming games, but this case is not expected to be pursued any further.