Rangers looked certain to suffer their first Championship defeat of the season when they trailed 2-0 to goals from Kris Commons and James Bailey.
But stoppage-time goals from Patrick Agyemang and Jamie Mackie stunned the Pride Park faithful to earn the visitors a point which keeps them top of the table.
Warnock said: "I think a lot of teams might have packed up at that late stage.
"But I said to the players before the game that there are going to be times this season when we go two or three-nil down.
"But I always think that we can get a result because I believe we are capable of scoring goals in a split second.
"I didn't realise it was going to be 90-plus minutes when we scored two goals but it just goes to show that you never give in," said Warnock.