Head coach Gary Thornton says the Dons must reduce their error count.
But he is not getting too disheartened after seeing his side lose to new League One leaders Toulouse.
Doncaster went down 46-26 at the Stade Ernest-Argeles on Saturday after trailing 28-6 at the break.
“If it had been 22-6 at half time I felt we would have had a real chance,” Thornton told Dons’ website.
“But we gave some sloppy tries away and the one on the stroke of half time was the sloppiest of them all.
“It could have been a different game, we have to work on rectifying these mistakes.
“I said before the game we would get punished by Toulouse if we made mistakes and all of their tries came off the back of a Doncaster error. I think that shows because of the full time training they have got, they are a very fit and strong team and they can capitalise on every error.
“If we can cut our errors out and react better to our mistakes and play like we did in the second half we are a match for anybody and we showed a lot of positive sides against arguably the best team in the division.
“In the second half we showed some great spirit,” he added.
“We got within six points at one stage and I thought an upset looked on the cards.
“I think the try just before half time was a sucker punch. I felt there were a few inconsistent decisions, but I’m not using that as an excuse.”
Defeat left the Dons fifth. The top four get home advantage in the play-offs.