Video: Celtic Park fumes as Motherwell score after refusing to give ball back
However, talk after the match was dominated by the goal the visitors scored six minutes into the second period.
Celtic had kicked the ball out of play after Ryan Christie pulled up with injury.
Motherwell took the throw in but, instead of throwing it back to Celtic, youngster James Scott tore down the wing on the attack.
His shot was parried by Scott Bain but the follow up saw Gboly Ariyibi fire into the net.
Celtic’s players, led by a furious Kieran Tierney, confronted their opponents but, as the laws of the game state, the goal was allowed to stand.
Celtic, who led 2-1 thanks to goals from Scott Sinclair and Odsonne Edouard, would eventually put the game beyond Motherwell as Edouard grabbed a second before Oliver Burke finished off the scoring.