The Liverpool loanee was introduced as a first-half substitute with his team trailing in their MLS match and produced a fine cross for an equaliser shortly before the hour mark.
Toronto went on to notch a winning goal and victory leaves Gallacher’s side in second spot in MLS’ Eastern Conference.
Elsewhere over the weekend, Sheyi Ojo and Kamil Grabara played in draws.
Ojo started Cardiff City’s goalless stalemate with Blackburn Rovers in the Championship, while Grabara’s first game of his second loan spell with Danish outfit AGF Aarhus ended 1-1 with Aalborg BK.
Two Reds Academy players suffered defeats, however.
Morgan Boyes completed the full 90 minutes as Fleetwood Town lost 2-1 to Rochdale, and Adam Lewis came on as a late substitute in Amiens’ 1-0 reverse to Caen.