Supporters were furious at the way their side played and perfectly illustrated just how far off the pace the side is.
Mohamed Salah scored a hat-trick as Jurgen Klopp's Reds enjoyed their biggest ever win at Old Trafford, which started emptying even before half-time substitute Paul Pogba was sent off for a foul on Naby Keita.
talkSPORT spoke to several fans who left the ground early and they were furious with what they saw from their players and manager Ole Gunnar Solskjaer.
"It's embarrassing, it's the worst display of football I've ever seen," one fan said.
When asked if they've ever left early before, they added: "No, never. You can see the way Liverpool play compared to Man United, they press, press and press and put pressure on us.
"We do nothing. We leave them so much space and let them do what they want with the ball.
"It's embarrassing. It's really really embarrassing. I've never left early before, definitely never left at half-time before.
"I'm sorry, Ole needs to go. I'm the biggest fan of Ole, I love him and he's a club legend. I will be forever grateful for what he did in '99.
"I love him to pieces, but as a manager he's not the man. We need a man who can manage a team and can change a team when things are down. He's not the man."
Another added: "I've never left Old Trafford early in my life and after Pogba's sending off we got back in the car.
"I'm not going to come on here and say it is purely Ole, because I really don't believe it is."
Solskjaer came in for plenty of criticism from supporters and calls are growing for him to go.
Another supporter who left Old Trafford early told talkSPORT: "Ole has lost the plot. The team are not playing for him now.
"First time ever we've walked out of a football game at Man United. They are not even trying."
Solskjaer himself believe he is still the man to take the club forward, despite the dreadful result and poor run of form.
Asked if he believes he still has that backing from above, Solskjaer said: "Well, I've heard nothing else [on my future] and I'm still thinking about tomorrow's work.
"Of course, we're all low. I can't say now that I've felt any worse than this. This is the worst I've been, the lowest I've been but, as I've said, I accept the responsibility and that is mine today and it's mine going forward.
"Today's rock bottom, low in confidence but next week it's Tottenham away, it's a Champions League game at Atalanta, the next team who visits us… that's Man City.
"We have to look forward, we have to sort the frames of mind out and make sure we go into the next training session and the next game with the right frame of mind."