Crescenta Valley Coach Phil Torres, whose team fell to 13-5, 5-1, raced out of the dugout and became involved in a heated discussion that lasted about two minutes. Torres was ejected and will be required to serve a mandatory one-game suspension against visiting Muir on Tuesday.
Trask (4-2) then set down the next two batters to put the Apaches alone in first place.
Torres, who briefly argued a first-pitch strike to Mulcahey with the home plate umpire, said he saw Mulcahey touch first base.
"He stepped right on top of the base," said Torres, who added it was the second time he's been ejected from a game in his 17-year coaching career. "It's a big game and the umpire became involved.
"I wasn't even thinking of Arcadia appealing. I was thinking about what our batters would do next. I shouldn't have lost my temper and it's both ways [with the umpire].
"It's a game that came down to one big mistake. Erik [Trask] pitched a great game. Give him credit."
Crescenta Valley starting pitcher Kyle Murray (3-3) did a good job keeping the Apaches, who have won three league championships in a row, off balance. The senior right-hander got into a jam in the sixth.
Murray struck out Brandon Benson on a 3-2 pitch, but the ball eluded catcher Cam Silva and Benson reached first successfully. An errant pick-off attempt by Murray eluded the first baseman and went down the right-field line and allowed Benson to reach third.
Murray got Troy Resch to fly out to shallow left for the first out. Trask then laid down a squeeze bunt between the mound and third base, allowing Benson to score.
"It's my fault," said Murray, who struck out 10 and scattered four hits. "I shouldn't have thrown the ball [on the pick-off attempt] in the dirt.
"There's nothing you can do about the squeeze."
Trask, a right-hander, struck out nine and limited the Falcons to two hits.
The Falcons' best scoring opportunity came in the second. Trask gave up a lead-off single to Murray and then walked Silva. Trask then picked off pinch-runner Bryce Foster at second before getting the next two batters.
Crescenta Valley and Arcadia will next meet at 7 p.m. May 11 at Stengel Field.
charles.rich@latimes.com