The incident allegedly began over an accidental bump in the shopping mall.
Two lanes were cordoned off by the Traffic Police.
MAS "deeply regrets" the inconvenience caused to passengers whose flights were cancelled.
Some people almost fell down, said witnesses.
Business has been brisk since the 27-year-old Malaysian's photos went viral online.
The rider was lucky to have found them before entering Singapore, netizens said.
She had the employees count the cash for nearly two hours and then left without buying anything.
No one was significantly hurt in either of the two fires occurring on the same day in Yishun.
"It’s the best birthday experience I ever had, not just once but three times," he said.
Dashcam footage apparently showed the driver returning to the scene about 15 minutes after the collision.