The husband and wife were travelling from Leeds to Pontefract when a group of three men and a woman boarded at Glass Houghton.
They teased the man about his ginger hair and glasses and he told them to leave him alone.
The gang then became aggressive and as the couple went to get off the train at Pontefract Monkhill, one of the men punched the woman, 47, in the chest.
They then followed the victims after they got off the train and attacked them from behind.
The man, 48, was knocked to the floor and kicked by the male members of the group.
When his wife attempted to stop them, she was pushed away and then attacked by the female member of the gang.
PC Sarah Donnelly, from British Transport Police, said: “Officers were called to the incident and attended but the group had fled the scene.
“This was a violent and unprovoked assault on a couple who were simply returning from a day out. If you know the people pictured, please contact us.”
Police have now released CCTV images of three men and a woman they would like to speak in connection with the assault.
Anyone with any information should call 0800 405040 or Crimestoppers, anonymously, on 0800 555111.