At 14:54 of the first period in the Penguins/Capitals game, Pittsburgh requested a Coach's Challenge to review whether Washington's Brett Connolly interfered with Pittsburgh goaltender Matt Murray prior to Jakub Vrana's goal.

After reviewing all available replays and consulting with the Referee, the Situation Room confirmed that the actions of Connolly did not impair Murray's ability to defend his goal and, therefore, no goaltender interference infractions occurred before the puck crossed the goal line.
Therefore, the original call stands - good goal Washington Capitals.
Since the Coach's Challenge did not result in the original call being overturned, the Pittsburgh Penguins forfeit their time-out.