Wrexham fans showed no sympathy for referee Sam Purkiss, who had to be replaced after suffering and injury in their League One clash on Saturday.
The official initially went down in the 11th minute and received treatment on the field of play. He continued and was in command as the two sides exchanged goals in a pulsating first half.
But 10 minutes before the break, Purkiss was unable to soldier on and was replaced by Alan Dale. He he left The Valley turf, the visiting fans could be heard singing 'You're not fit to referee.'
Wrexham had travelled to the south east looking to close the gap to league leaders Birmingham to just two points, following the Blues' lunchtime draw with Mansfield Town.
Conor Coventry's 16th-minute own goal got them off a good start but Phil Parkinson's side were quickly pegged back by Macaulay Gillesphey's leveller.
Wrexham fans could be heard chanting 'You're not fit to referee' as he was replaced by fourth official Alan Dale
The visitors again got themselves in front when Andy Cannon fired home in the 72nd minute but Matt Godden ensured the points would be shared when he converted a 97th-minute spot-kick.
Wrexham have picked up seven wins, four draws and two defeats from their opening 13 League One matches.
They have also lost just one of their last seven games in all competitions - since going down 3-1 to pacesetters Birmingham in September.