An elderly bus passenger died after falling from the open door when it went forward because the driver had failed to put the handbrake on, a court was told.
John Childs, 73, who used a walking stick, argued with the driver, Christopher Balding, because the bus did not stop where he was expecting because of roadworks in Harlow, Essex.
Chelmsford Crown Court heard that the vehicle stopped "several hundred feet further along" on Howard Way.
Michael Shaw, prosecuting, said Mr Childs rose from his seat and appeared "not best pleased the bus had not stopped at the stop he hoped it would".
He said the doors opened and, with Mr Childs standing in the gangway speaking to the driver, the bus "lurched" forward.
Mr Shaw said "Mr Childs, who was unsupported, falls back against the open door, toppled out of the gangway and landed heavily in Howard Way".
The pensioner suffered a brain injury in the incident on May 3 2019 and died in hospital on May 12.
Mr Shaw said that the single-decker bus, operated by Arriva, was an automatic, adding: "The handbrake wasn't applied when this bus stopped on 3 May and therefore the driver's foot coming off the brake, as it clearly did for some reason, caused this bus to move forwards.
"That's what caused Mr Childs to lose his balance and topple through the open door."
He told the court that when the bus moved forward, Balding "reapplied the foot brake immediately, which caused the bus to suddenly jolt to a stop".
Three police officers, who were on duty in a marked van nearby, gave first aid to Mr Childs within seconds.
One of the officers, PC Chris Oliver, told the court that Balding, 39, "seemed very stressed and upset and wasn't sure what had happened".
The officer said, in answer to a question from defence barrister Matthew Bagnall, that he detected alcohol on Mr Childs's breath.
Balding said, in a police interview read in court, that, when Mr Childs realised the bus was not going to stop at the stop he wanted he began directing abuse at the driver and used an expletive.
Balding said he had seen Mr Childs on several occasions before and "never had any issues with him".
He said he did not remember using the handbrake, and suggested his foot may have come off the brake as he turned towards Mr Childs.
Balding, of Quarry Spring, Harlow, denies causing the death of Mr Childs by dangerous driving.
The trial continues.