Eddie Howe was left fuming at Anfield after Liverpool's equaliser stood despite Isaac Hayden lying injured on the floor.
The Newcastle United boss and his coaching staff protested at the time as Diogo Jota levelled the game up.
But Wirral-based referee Mike Dean allowed the goal to stand before Liverpool went on to claim a 3-1 win.
Howe said: "In my opinion the game should have been stopped before their equaliser with two players down.
"Two players down in the box and it had a huge bearing on our game plan.
"As soon as they score the crowd are in the game and it feels unjust.
"The referee said he thought he was holding his back but Isaac Hayden held his head, he was dazed for four or five minutes.
"It could be dangerous and we have to think of the player's safety, you also don't want to see games decided when you have players out of the game."
Meanwhile, Trent Alexander-Arnold had his say on the incident and reflected: "You're not really looking at who's on the ground, who's up.
"But if it's a head injury it's down to the referee to stop it.
"He didn't. We played to the whistle and scored.
"We didn't cheat or do anything unsportsmanlike."
