The Red Devils saw Ander Herrera withdrawn early in the game before Juan Mata was also forced off, as caretaker boss Ole Gunnar Solskjaer's tactical set up went right out of the window.
Mata's replacement Jesse Lingard was also taken off before the interval, seemingly aggravating the injury he picked up against Paris Saint-Germain two weeks ago.
The contest became a scrappy, stop-start affair as a result of the changes, with Liverpool's Roberto Firmino also hobbling off for the visitors in the 31st minute.
Shaw offered an insight into the 'crazy' mood of the United squad during the break with the scores locked at 0-0, insisting that they were lucky to still be level after surrendering possession of the ball for large periods.
"We gave too many balls away too cheaply and luckily that didn't cost us. But we had a change of formation, we had a good chat at half-time. Everyone was going crazy.
"We said 'relax and we just need to play our game' and I think the second half was better.
"We still weren’t at our best but overall I think we created the best chances and I feel we should have won."
Tough game but Old Trafford was buzzing 👏🏼 pic.twitter.com/8nKEh4TKgJ— Luke Shaw (@LukeShaw23) February 24, 2019
Marcus Rashford also seemed to be struggling with his mobility throughout the game, but with no substitutes left available to Solskjaer in the second half, the 21-year-old soldiered on.
Despite the unusual nature of the match, Shaw managed to keep Liverpool talisman Mohamed Salah quiet all afternoon, but he feels he can still take his game to another level yet.
“We all know how unbelievable Liverpool's attack is and I don't even think David (de Gea) had a save," Shaw continued.
"So, that's credit, not just to the back five, but the whole team for doing their job.
“These are the games that you want to try to step up in - you want to try and prove why you're here.
"You want to play against the best, you want to test yourself against the best and I want to keep doing that in my career.
"I think I've still got another level to come. I don't think I am really at my best and I know what I can do when I'm at my best."
United are now sweating on the fitness of their crocked quartet ahead of their next Premier League fixture at Crystal Palace on Wednesday.
Solskjaer has overseen a superb run of 11 wins from 14 matches across all competitions, but the Red Devils surrendered their place in the top four to Arsenal after their latest result.