Each week during the Australian Football League (AFL) season, Sheahan interviewed a figure in the history of Australian football, discussing their involvement in the game, whether on-field or off-field, as well as their lives and contributions away from the game.
[1] Guests have included former champion players Kevin Bartlett, Leigh Matthews and Bob Skilton; coaching greats Kevin Sheedy, David Parkin and Malcolm Blight, and media personalities Tony Charlton, Eddie McGuire and Sam Newman.
Former chief executive officer of the AFL Andrew Demetriou, former Sydney premiership coach Paul Roos, and Kevin Sheedy have also appeared twice in two separate episodes.
In October 2020, it was announced by Fox Footy that Sheahan would be retiring after an 11 year stint at the station, thus concluding Open Mike.
In a fitting farewell, the 234th and final episode turned the tables on the long-time presenter, with the longtime presenters of fellow Fox Footy program AFL 360, journalists Gerard Whateley and Mark Robinson taking the hosting role and interviewing Sheahan.