After returning to Celtic, on 28 January2011 Mišůn apparently joined League One side Swindon Town for an undisclosed fee - however, it was later revealed he had not officially signed a contract.
Mišůn was a member of the Czech under-19 team and made six appearances, his last being in a 5–1 win against Estonia on 26 May 2009. He scored one goal, a shot from 25 yards against Spain on 23 May 2009. He has played at under-20 level for his country.