Spurs had totally dominated the contest and should have been well clear heading into the closing stages, with Son hitting both bar and post in the first half.
But in the final minute a header back across goal by Andy Carroll struck the back of Eric Dier's arm, and after a lengthy consultation, a penalty was awarded, which Callum Wilson slotted home.
It was Newcastles only shot on target in the contest and at full-time, Mourinho had seen enough, heading to the dressing room while the final whistle sounded.
Jamie Carragher's commentary on Sky Sports made his feelings clear, branding the decision a 'disgrace' and 'a joke'.
Quite simply, the game’s gone.— Football Index 🎂 (@FootballIndex) September 27, 2020
It is one of a number of controversial handball decisions after the new regulations were introduced this season, with Manchester United falling victim to a Victor Lindelof call last weekend versus Crystal Palace.
Roy Hodgson, meanwhile, blasted the regulations yesterday saying that 'they are killing the game'.
Mourinho was clearly angry but did not want to discuss the incident after the game for risk of receiving a fine, saying: "If I give money I'd rather give it to charity than to the FA."