Vidic was booked later on in the game at Wembley, so if the referee had shown Vidic a yellow he would have been sent off later on in the game.
It will come as no surprise that Villa boss Martin O’Neill believes that Vidic should have been sent off and that the ref bottled it.
O'Neill said: "It was plain for all to see. It's an inexplicable decision. There was a goalscoring opportunity in the area.
"It was a mistake from an otherwise very fine referee.
"There's no other decision. It's the major point of the match.
"Anybody would be wondering how he could come to any other conclusion.
"It doesn't matter whether it's the first or 90th minute. It is straightforward - so straightforward it is incredible.
"It's hard to take. I thought we played splendidly, particularly in the first half.
"I'm disappointed for the team but they're resilient, they're strong, they're young and they will fight back."
It will also not be a shock that Vidic himself said after the game that the referee was right not to show him a red card.
Vidic said: "It was a hard game but we deserved the win today.
"I can run better for the goal they scored. [Gabriel] Agbonlahor did well but like I said it’s a team game and I’m very proud.
"I got in front of him, not behind and did a tackle. If I had been behind, then yes.
"He was away from the goal. That is my opinion. We'll see better on the video."
Man United manager Sir Alex Ferguson has said that Vidic was very lucky not to receive a card.
Fergie said: “I’ve not seen it but he was lucky not to be booked anyway”
“There’s been three or four in the last week that’s been similar to that. The one we saw in Milan with Kalou brought down which to me looked like a penalty.
“You had one on Saturday which was a claim for an Arsenal player. It’s very difficult for the referee. Then Belletti bringing down Bellamy gets a red card.”
Finally, former referee Graham Poll has had his say on the issue, saying:
"The referee would have looked for an excuse not to send the player off, and that doesn't matter if it was an Aston Villa player or a Manchester United player.
"People will say that is rubbish, as there is nothing about a cup final in the rules but you try to use your common sense and understand the occasion.
"There was a technicality that allowed him to keep Vidic on and he used it.
"The player must be heading towards goal, it's a stupid technicality, but he [Agbonlahor] loses control of the ball and it goes behind him and at the moment he goes down he is heading six or seven yards wide of goal."
We all have our opinions on whether or not Vidic should have been sent off or not and they will differ depending on what team you support. When Phil Dowd pointed to the penalty spot, my immediate thought was that Vidic was going to be sent off, him not being shown any card did come as a surprise.
A sending off may or may not have affected the game, a few weeks ago we played Villa in the Premier League at Villa Park, not long into the match Luis Nani was sent off. Even though we were down to 10 men for a long time you wouldn’t have noticed that Villa had the extra man.
It would have been difficult for United to play with 10-men for 86 minutes and maybe the referee did use the ‘technicality’. For once I agree with Poll, I don’t believe that it was just because it was a Man United player, if it was the other way round, I believe he would have done the same thing. It is just unfortunate for Villa that it was so early on into the game.
I also believe that he should have been shown a yellow, not a red.
If they had gone on to win the match would people really be complaining? Would there have been complaints if he was shown a yellow?
