Fer found the Cardiff net in stoppage time, only for referee Mike Jones to rule the strike was not valid, leading Mackay to praise the official and lambast Holland forward Fer.
Cardiff goalkeeper David Marshall had thrown the ball out due to an injury to Norwich midfielder Alex Tettey and Ricky van Wolfswinkel's throw in went to Fer, who tucked into the bottom corner as Marshall awaited a return pass, sparking a fracas.
Fer, a summer signing from FC Twente, insisted he had done nothing wrong.
"I just looked at the referee and he did 'play on' with his hands so I think the goal had to count," Fer said.
"I'm a little bit confused on that one. I meant to put it in because I wanted to win the game."
The result should have been settled in Norwich's favour long before the moment which was reminiscent of Kanu's goal for Arsenal against Sheffield United which was so contentious it resulted in an FA Cup replay in 1999.
The Canaries found their former goalkeeper Marshall in fine form and missed a host of chances to claim a third win of the season, leaving them in the relegation zone.
Manager Chris Hughton was the subject of the supporters' ire, particularly after substituting Gary Hooper, who had numerous opportunities to net his first Premier League goal and was getting closer and closer as the match progressed.
Hughton said: "They're a fanatical and emotional support and any frustrations they have is because they want to see us win a game. They would be the exact same frustrations that I would have.
"I never have any problems with a reaction from the support, because what it does do is show that they care."
Hooper was replaced by Johan Elmander while Van Wolfswinkel was held back until three minutes from time, with Hughton reluctant to exacerbate his record signing's toe problem.
Defender Michael Turner believes Norwich's luck will turn after strong displays in a win at Stoke, a 3-1 loss to Chelsea, a 4-1 defeat by Arsenal and against Cardiff.
Turner said: "The amount of chances we created it's ridiculous the fact we haven't scored.
"That's what happens. You have to make these things happen and make your own little bit of luck.
"It's not a place we want to be (relegation zone), but the last four performances have been excellent at times.
"I'm confident if we keep playing the way we are, we keep progressing, then we'll pick up wins."
It does not get any easier, though, with a trip to Manchester United in the Capital One Cup on Tuesday night followed by a Premier League clash at Manchester City next Saturday.
"It's an exciting week for us," Turner added.
"(There is) no pressure on us going to Old Trafford in the cup game, no-one's expecting us to do anything there.
"Hopefully we can go up there and play the way we have done in the last few weeks."
Mackay was pleased as Cardiff picked up another point away from home following the draw with Hull and defeat of Fulham.
"It's a clean sheet, it's our fifth point away from home and I'm delighted with that," former Norwich defender Mackay said.
"I spoke to a couple of Premier League managers pre-season who talked about the importance of picking up points away from home and how difficult it is away from home at any ground in this league.
"I know Carrow Road really well, so to come away with a point and the way we defended, I was delighted."
Mackay reserved particular praise for Marshall.
"He's someone whose confidence had been knocked when we arrived," Mackay added.
"He's worked hard, he's got himself back into the Scotland squad. He's a very level-headed young lad who has done excellently since the day I walked. He's an excellent goalkeeper."