Two first-half headers from Oriol Riera had put the hosts in control and things went from bad to worse for Madrid when Ramos was shown his 18th red card for the club a minute before half-time.
However, Isco pulled a goal back for the visitors before the break and after Osasuna had also been reduced to 10 men by Francisco Silva's dismissal, Pepe headed home the equaliser 10 minutes from time.
Ancelotti's men did have legitimate reasons to complain about the performance of Gomez as both of the yellow cards shown to Ramos appeared harsh, while he also waved away a strong penalty claim after Alejandro Arrbias had upended Luka Modric with the score at 1-0.
And the Italian said he felt Ramos in particular had been hard done by.
"I don't like to talk about the referee's decisions, but it was a difficult decision to understand. The first (card) is not even a foul. I don't know what happened."
Real keeper Diego Lopez was stronger in his criticism of the referee for not spotting the foul on Modric inside the area.
"We knew that coming here was going to be difficult. It wasn't our best match, but the game was conditioned by the referee's decisions, or rather the ones he didn't make. I have seen that it was a penalty on Luka," the told reporters.
"We had some very clear chances early on and the game would have been different if we had taken them. Then they scored two goals and in the second-half at 2-1 we had to come out and fight. We are upset because we have lost two points, but the important thing is that we fought till the end."
Ancelotti also praised the response of his players after falling two goals and a man down.
"We lost a bit of control of the game after the first goal because we had played very well and with a lot of quality in the first 20 minutes," he said.
"It was incredible to be 2-0 down with 10 men towards the end of the first-half given how we had played. The team showed great character and attitude to come back and draw the game."
Madrid's draw allowed Barcelona to extend their lead on their eternal rivals with a 2-1 win over Villarreal at the Camp Nou.
Neymar was once again the star man for the Catalans in Lionel Messi's absence as he scored twice either side of Mateo Musacchio's equaliser for Villarreal early in the second-half.
And having responded to two consecutive defeats with three straight wins in the past week, Barca boss Gerardo Martino is disappointed that La Liga will shut down for two weeks following next weekend's trip to Getafe.
"It is a shame that the league will stop because we are in good form. After playing against such a difficult opponent and playing three very good games in a row, I wish we could postpone Christmas," he said.