Kick-off for the Barclays Premier League meeting, the last at Upton Park before the Hammers move to the Olympic Stadium in the summer, was delayed until 8:30pm after United’s players did not reach the ground until 7:10pm.
The coach had to battle through throngs of West Ham fans gathering outside the stadium as they prepared to say goodbye.
As the driver manoeuvred his way through the car park gates, the coach was pelted with glass bottles and other missiles - breaking and damaging the tinted windows, with one police officer and a member of the public suffering minor injuries.
Sullivan was drafted in to speak to several media outlets after the delay was announced and was not happy with what he deemed to be a late arrival from the United contingent - with West Ham’s pre-planned 45-minute post-match celebration put at risk.
“It is depressing really,” he told BBC Radio Five Live.
“It will be a late night for our fans and some of them won’t be able to stay. I don’t understand why United couldn’t get here at 4pm. They could have got here early. They knew it would be busy. It’s crazy.
“There was congestion in the street and they couldn’t get the coach in. There were people around the coach, but there was no attack on the coach.
“If you check the coach there won’t be any damage to it. If we arrived late at Old Trafford they wouldn’t put the kick-off back.”
He also told Sky Sports: “I think the police and officials have been kind. I’d make them kick off at 7.45pm if I was in charge.
“I’m gravely disappointed, more for our supporters. What people forget is they’ve got trains and buses to get home and we’ve got a wonderful, wonderful show after the game for them. Many just can’t stay any more.”
The Metropolitan Police confirmed that one officer and a member of the public sustained minor injuries in the trouble.
A statement from the force said: “We are aware that a number of items were thrown towards Manchester United’s coach this evening, Tuesday, 10 May.
“One police officer and a member of the public sustained minor injuries.
“There have been no arrests.
“An appropriate policing plan is in place.”
United captain Wayne Rooney spoke of the situation after decamping from the coach and entering Upton Park for the last time.
“It wasn’t nice,” he said.
“The coach got smashed up, but we’re here now, so have to prepare for the game and go out and do our job.”
“I’m sure you’ll see the images. That’s not for me to say, but I think it was disappointing of course.
“We know it’s a big game for West Ham, big night for them, leaving the stadium, but I’m sure West Ham as a club will be disappointed with what the fans have done.”
The Red Devils have form for arriving late, with their game at Tottenham last month also delayed following traffic problems.
Manager Louis van Gaal suggested the incident could have an impact on his players as United go in search of a victory to keep a top-four finish in their own hands.
‘’What do I have to tell? The images tell everything,’’ he told Sky Sports.
‘’I have seen also the police were taping. It is also a lot of emotions for people but for us it is the second time in London we have to start later. It is better than last time because we have received our preparation time.
‘’It is not the first time I have seen that. It is not so nice. The way we have been received is not the proper way, of course. That makes all the influence on the players and that is a pity.”