DeMarco Murray's 1-yard run late in the first half began the rally for Dallas (2-1). Dez Bryant caught a 68-yard scoring pass in the third quarter, and Carter's first career interception and touchdown came not long after he was evaluated for concussion-like symptoms on the bench.
The comeback matched the largest in Dallas history, the other two coming in overtime in 1984 against New Orleans and 1999 against Washington. It tied the second-largest lead blown by the Rams, who slowed Murray but got burned everywhere else.
St. Louis is 0-2 at home and was whipped 34-6 by Minnesota in the opener.
