Cameron Harper has been credited with two goals but from the video it looks like Mikey Johnston got a clear touch on the goal that put Celtic 2-0 in front.
Firth didn’t look too clever at the third goal either as Harper cut in from the right wing to fire a past the keeper from a tight angle.
Celtic have now topped the Round Robin section of the tournament to book their place in the final at Broadwood next month where they will meet the Ibrox kids again if they can overhaul Partick Thistle’s three point advantage with two matches left to play.
CELTIC: Olewayemi, Otoo, Montgomery, Murray, Welsh (McPherson 55), Connell, Harper, Coffey, Oko-flex, Dembele, Johnston (Moffat 46)
Subs: Angelini, Wylie, Carse, Brooks, Davidson