Speaking on Sky Sports earlier this week, Merson said: "If Andros Townsend can get in [the squad] then it opens it up for anybody."
But after Graziano Pelle opened the scoring for Italy with a first-half header in Turin, substitute Townsend rescued a draw with a superb 79th-minute strike.
Taking to Twitter shortly after the final whistle, Townsend posted: "Not bad for a player that should be 'nowhere near the squad' ay @PaulMerse?"
And manager Roy Hodgson says his side are "indebted" to Townsend for restoring parity following a disappointing first half.
"It means a lot to us," he said. "It is no mean feat, to come to Italy and get a result, especially to take the game to them like we did.
"We are indebted to Andros. I haven't forgotten the first half, we can't allow that to happen. I don't think anything was good enough.
"We were lucky they were pretty tame as well."
