Ten-man Boston kept their unbeaten home record intact with a draw.
Boston defender Lee Beevers was sent off in the first-half, retaliating following a foul by David Artell after being booked earlier.
The tackle earned Boston a penalty, but after all the furore and Beevers' dismissal, Tam McManus saw a tame spot-kick saved by Kevin Pilkington.
Mansfield went close when Artell shot wide, with Alex Neill and Colin Larkin also testing keeper Nathan Abbey.
Boston Utd: Abbey, West (Melton 45), Beevers, Ellender, McCann, Thompson, Noble (Rusk 42), Greaves, Thomas, Lee, McManus (Clare 69).
Subs Not Used: Strong, O'Halloran.
Sent Off: Beevers (37).
Booked: Beevers, Rusk.
Mansfield: Pilkington, Buxton, Artell, Baptiste, Talbot, Neil, MacKenzie, Curtis, McLachlan (Murray 29), Corden, Larkin.
Subs Not Used: Dimech, Lloyd, Hankey, White.
Booked: Curtis, McLachlan, Artell, Corden.
Att: 3,354.
Ref: M Warren (W Midlands).