During his time with the Mets, Castillo helped end one of the longest scoreless opening day games in MLB history. On March 31, 1998, he hit a full-count, two-out, pinch-hit single to right with the bases loaded in the bottom of the 14th inning to help the Mets beat their division rivalPhiladelphia Phillies 1–0 at Shea Stadium.[1][2]
The Boston Red Sox organization signed him to a minor league contract on December 20, 2006, and invited him to participate in the Red Sox' 2007 spring training.[3]
He was used in the 2007 season by the Orioles to fill in for injured catcher Ramón Hernández twice and was designated for assignment twice after Hernandez's return. Castillo became a minor league free agent after the season. Castillo was the captain of the Dominican Team in the 2007 Caribbean Series.
On February 14, 2008, Castillo signed a minor league contract with the Houston Astros and was invited to spring training. After spending spring training with the Astros, Castillo was demoted on March 24 to the minors and later released. Confusingly, the Orioles signed a pitcher named Alberto Castillo at the beginning of the 2008 season.