In a trial  for World Cup selection in 1971, Mullins suffered a broken jaw and again, in 1973 when he was 'king hit' in a game against Manly-Warringah costing him any chance of being selected to the 1973 Kangaroo tour.
During a World Cup selection trial in 1971, Mullins suffered a broken jaw and, in 1973, he was severely injured during a game against Manly-Warringah, which ended his chances of being selected for the 1973 Kangaroo tour.