The midfielder - out since early last month with a calf problem - struck a superb goal before being substituted at half time.
With Adam Sadler's side trailing to a first-minute strike from Sean Evans, Emre took a pass from Andy Carroll outside the box in the 25th minute, played a one-two with Wesley Ngo Baheng and rifled the ball past Ron Robert Zieler in the visiting goal.
Three minutes from time Man United's Richard Eckersley received a straight red card for bringing down Kazenga LuaLua just outside the box, and Ngo Baheng got a second yellow for his involvement in the fracas that followed.
Fit again Peter Ramage and new signing Lamine Diatta played the full 90 minutes of the fixture, which wrapped up Newcastle's league campaign.
2,839 watched the game.
Newcastle Reserves: Forster, Ramage, Kadar, Edgar, Diatta, Tozer, Troisi, Emre, Carroll, Ngo Baheng, LuaLua.
Subs: Danquah, Soderberg, Marwood, Morri, Zamblera