Businessman Sean Quinn Jnr was questioned by gardai at the weekend after being accused of drunkenly abusing other passengers.
The 33-year-old was travelling from Westport, Co Mayo to Dublin when passengers complained to the driver about his behaviour.
Gardai were called and he locked himself in a toilet before being escorted from the train at Tullamore, Co Offaly.
He was arrested and taken to the local garda station before being given a caution.
It is understood he then made alternative transport arrangements to complete his journey.
The son of bankrupt businessman Sean Quinn, Mr Quinn Jnr was travelling on board the 13.15 train from Westport to Dublin on Sunday afternoon when the incident occurred.
Repeated attempts to contact him for comment yesterday were unsuccessful. A spokesman for Iarnrod Eireann confirmed that a man was asked to leave the train in Tullamore, adding the service was delayed for almost 15 minutes.
"One person was removed from the train," he said. "Other passengers complained and the driver asked for gardai to be called. When the train arrived in Tullamore, the gardai sought to remove him from the train.
"The person locked himself in the toilet and resisted arrest. He was handcuffed and removed from the train. He was drunk and being verbally abusive to other people on board."
Mr Quinn Jnr has been embroiled in his family's legal difficulties and was jailed last year.