Flanagan flew into former Liverpool man Raheem Sterling within the opening seconds of the contest, which immediately got the crowd involved.
Henderson believes it was a pivotal moment in the game, as the Reds completely dominated the two-time Premier League winners on Merseyside.
“I think Flanno definitely set the tempo of the game, the fans lifted that extra little bit, and from that point the whole team lifted, so that was a big moment in the game,” Henderson said post-match.
“There are a lot of players who came in who didn’t play at the weekend and they’ll have been disappointed that they didn’t play but they’ve channelled that in the right way. They were outstanding.”
“We felt they took something from us at the weekend that maybe we deserved, but tonight we made sure that we took the three points.
“We knew that we had to bounce back from the weekend in very difficult circumstances with only three days between.
“Our focus was just solely on winning the game and I thought it was a brilliant performance as well.”
Lallana was one of Liverpool’s star men on the night, in what was arguably his finest performance for the club to date.
The 27-year-old was equally delighted with the win, and felt many Reds players both shone on the night and responded from the heartache of Sunday in style.
“Throughout the team I thought there were great performances”, he also told Liverpoolfc.com.
“Flanno, coming in, I thought he was excellent, Kolo, Dejan coming back in after a while out and Clyney filling in at left-back – I thought they were outstanding.
“The manager said he wanted to see a response, he wanted it to be intense, and I thought it was a great atmosphere out there, the crowd responded.
“It’s not nice to lose cup finals but throughout the team we’ll learn from it and hopefully there’ll be more finals in the near future. It hurt at the weekend, no doubt about that.
“The lads that missed penalties, including myself, might have felt a bit of guilt for missing the penalty.
“But the lads have been great, we’re in it together, and I thought we contributed this evening together as a unit and put on a good performance for the fans.
“There were great performances all throughout the team tonight and I think we just need to continue that and be a bit more consistent.”