Motherwell goal offside?

53 minutes played Motherwell 1-0 up against Rangers. Free kick sent into box, all Motherwell players on side, Motherwell player hits a shot, all Motherwell players on side. Goalscorer knocks it in Ass. Referee John Gilmore flags for offside, referee Callum Murray agrees and goal is not given. Game ended 1-1 on the same night Celtic beat Hearts 2-0.

bbc Scotland website commentary of game.

" 53:58 The referee blows for offside against Ross Forbes. Free kick taken by Allan McGregor."