Barrett ran back an interception and Bell brought back a fumble for a score, two of the four mistakes forced by Colorado State (3-7, 2-4 Mountain West). Donnell Alexander ran for a career-high 139 yards, his second straight 100-yard game, and two touchdowns.
The Rams had lost seven of eight.
Tim Cornett ran for 102 yards on 20 carries for UNLV (2-9, 2-4). Cornett became the first Rebel to have eight 100-yard games in a season since Icky Woods did it in 1987. Nick Sherry was 12 of 30 passing for 139 yards, a touchdown and two interceptions.
The Rebels haven't won at Hughes Stadium since Nov. 20, 2002, and extended their road losing streak to 21 games. They failed to win back-to-back games for the first time since 2008.