Castellanos got the scoring started in the 33rd minute, dribbling through three defenders in the box to make his way to an unassisted goal and leave Iona (4-0-0) with a 1-0 lead after the first half.
The Mountaineers (1-3-1) rallied to grab a 2-1 lead in the first three minutes and 40 seconds into the second frame. Chris Wheeler knotted the game at one off helpers from Ian Hendrie and Zoncher Dennis at 46:02 before Hendrie handed the Mount a 2-1 edge off a feed from Patrick Wheeler at 48:40. Iona responded to even the match at 2-all when Castellanos set Torrecilla up for his first of two tallies on the day in the 58th minute.
The two sides then traded goals, scoring within three minutes of each other. Hendrie scored off a loose ball following a free kick by Wheeler with just under five minutes remaining in regulation, giving the Mountaineers a 3-2 edge. With only 1:29 to go in the second half, Alexander Abdalla tied the match on his first goal of the season with help from Samuel Adjei and sent the contest to overtime.
Torrecilla scored for the second time on the day at 96:44 to give the Gaels the victory.
Iona led Mount St. Mary's 15-9 in shots and 4-1 in corner kicks in the game. Rookie goalkeeper Borja Barbero made two saves in his fourth career win. Peter Steve stopped five for the Mountaineers.
The Maroon & Gold is off to its best start since opening at 3-0 in 2009. The squad wraps up its five-game road set next weekend in the Rutgers/St. John's Nike Soccer Classic. Iona is set to face Rutgers on Sep. 16 and St. John's on Sep. 18.