At 3:01 of the second period in the Flames/Bruins game, Calgary requested a Coach's Challenge to review whether Brad Marchand interfered with goaltender Chad Johnson before the puck entered the net.
The Referee determined that Marchand initiated contact with Calgary's Mark Giordano and propelled him into Johnson before the puck crossed the goal line. According to Rule 78.7, "the standard for overturning the call in the event of a 'GOAL' call on the ice is that the Referee, after reviewing any and all available replays and consulting with the Toronto Video Room, determines that the goal should have been disallowed due to 'Interference on the Goalkeeper,' as described in Rules 69.1 and 69.4."
Therefore the original call is overturned - no goal Boston Bruins.
Since the Coach's Challenge resulted in the original call being overturned, the Calgary Flames retain their time-out.