Tens of thousands descended on the Theatre of Dreams for the culmination of United’s season - only to not see a ball kicked in anger.
Manchester United’s global fan base meant some supporters had jetted in from as far afield as Sierra Leone and Azerbaijan.
Litigation lawyer Mark Stephens said: “It struck me, there’s a complete raft of legal claims here.
“I imagine there’s going to be a class action here on behalf of all the fans who have been disturbed. There is also the question of distress caused.
“We are certainly talking millions.”
The alert was sparked after a fake bomb was accidentally left in a toilet after a security training exercise last week.
It was only discovered 20 minutes before kick-off and thought to be real - prompting a mass evacuation of 75,000 fans and the match abandoned.
The company responsible for the dummy explosive is believed to be Security Search Management & Solutions Ltd.
It is understood Security Search Management & Solutions Ltd was hired by Deacons Canines to carry out practical training exercises for sniffer dogs at the stadium.
Mr Stephens said the legal test for claims would be if there was negligence in not counting out and counting back in the fake devices used in the exercise.
If negligence was established then a “broad swathe of fans” could have legitimate claims to make against the firm responsible for the fiasco.
Mr Stephens continued: “Fans would be entitled to make a claim - I suspect the firm will be insured for public liability.
“If the insurers accept liability they would just make arrangements to pay out.
“There’s going to be literally millions in terms of travel costs and disturbance costs which can be used against people if they were negligent in not counting back in and out the fake devices.
“Clearly a lot of fans will re-appear, they don’t have costs beyond travel costs, some would not be able to come again - they will be entitled to compensation for travel costs, their disturbance, travel time and the disappointment of not being able to be present for the match.”
Manchester United must be “up front” with answers about the “shambolic” security scare, the city’s police and crime commissioner has said.
Tony Lloyd, who is also the mayor of Greater Manchester, said the club’s reputation and public safety had come under scrutiny.
Mr Lloyd said it was “astonishing” that the dummy bomb was not found earlier and the alarm raised only 20 minutes before kick-off, with thousands of fans already in the ground.
Meanwhile, United’s opponents Bournemouth have offered free coach travel to supporters for the 500-mile round trip journey to the rearranged game on Tuesday.
And United have offered a refund to all fans inconvenienced, as a well as free ticket for Tuesday.
Manchester United will also face additional costs to re-stage the game such as printing tickets and paying for stewards and police, Mr Stephens said.
It is not yet clear who will foot the bill for the Army Bomb Disposal unit being called out and the extra police, fire, ambulance and helicopter deployed once the Code Red alert was called.
Tony Lloyd, mayor of Greater Manchester and the Police and Crime Commissioner, said who pays will be a question that must be tackled once the club’s investigation has taken place.