At the time, the official didn't see the shot enter the net, but Nick Paul, who was right at the top of the crease, saw the puck over the goal line and began to celebrate. The officials took a quick look at the replay, which showed the puck completely across the line, tying the game 2-2 at the 19:28 mark of the first.
Then, in the second period, the Bolts grabbed their first lead of the night off a beautiful goal from Darren Raddysh, the first of his NHL playoff career.
Following a clean faceoff win from Steven Stamkos in the offensive zone, Nikita Kucherov dropped a backhand pass for Raddysh, who skated behind the Toronto net and fought through a check from Jake McCabe.
From there, Raddysh curled towards the goal at the left circle and ripped a quick wrister top shelf to give Tampa Bay a 3-2 lead with 6:26 remaining in the middle frame.
The Lightning dominated the second period, and as that dominant play rolled on, it looked as though Tampa Bay may take a 4-2 lead into the intermission.
With the Bolts on the power play, a clearing attempt from TJ Brodie deflected off Brayden Point in front of the net and ended up under the left pad of Samsonov, who had no clue where the puck was.
Samsonov never covered the puck. The puck deflected off Point, rolled off the right pad of Samsonov, and ended up right between his legs before Point jammed it into the back of the net. But once the official lost sight of the puck, he blew the play dead.
After they took a second look at the replay, the official claimed, "The puck was covered, therefore there is no goal." But the puck was never covered.
"I have zero idea why he blew the whistle," said Lightning head coach Jon Cooper. "It's shocking. The entire building, there was 20,000 people saw it was sitting right there. What I don't get is I don't know what the ref had to gain by blowing the whistle.
"Listen, that's not why we lost. You can look back now, but I just don't get it. You go through the league of quick whistles, that has to be the number one in the league.
"I just didn't know what he was gaining by blowing it so fast. It was clearly, the way the puck was delivered to the net, it was bouncing all over the place.
"Obviously unfortunate for us, but again, not why we lost. It helped, but that's not why we lost."
Following the disallowed goal, the Bolts headed to the locker room with the 3-2 lead and one period to go.
Then, with 15 minutes remaining in the third period, things got ugly.
As Point and Morgan Rielly both pursued a loose puck in the corner, the two collided and Rielly gave a shove to Point, who lost his balance and slammed hard into the end boards.
From there, Kucherov jumped in and threw Rielly to the ice as everyone came together and the whistle blew with Point down and injured. Responding to what most thought may be a major penalty at the time, Stamkos grabbed a hold of Auston Matthews and began throwing punches while Raddysh landed a big uppercut on Rielly that sent the Leafs defenseman to the locker room with a bloody jersey.
"You see one of the best players in the world go headfirst into the boards, there's got to be a response," Stamkos said. "I'd expect the same thing from their group if Mitch Marner or Matthews was in that same position."
When it was all said and done, it was Toronto that ended up with the man advantage and no boarding call was assessed to Rielly. Cooper said he received no explanation from the officials.