The incident took place on Saturday night.
Four men were arrested at Sallins, Co. Kildare train station at 9.30pm on 7 April after a fight broke out on a train travelling from Westport to Dublin.
The men, all in their 20s were detained for public order offences, while on board.
Two men were charged and released on bail, while another two remain in custody.
They are expected to appear in Naas District Court on Monday, 9 April.
Gardaí have stated that there was no stabbing or assault.
