Tom Felton’s addition to the cast of “The Flash” made Season 3 more momentous for Tom Cavanagh.

In the “Behind the Season Finale” featurette for Season 3 of the CW series, Cavanagh reveals that seeing Felton’s excitement off the camera was one of the installment’s “salient highlights” for him.

“[In Season 3, episode 19,] there was this moment where we put our hands together and we do like, ‘For Team Flash,’” says Cavanagh in the clip. “Watching how excited Tom Felton, the person, got to play Julian Albert, the character, and how excited he was to be a member of Team Flash was one of the salient highlights of Season 3 for me, watching this guy be excited for something we were doing together as a group.”

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Felton explains his enthusiasm by saying that he’s a fan of the show long before he joined the cast. “It was like episode 8 or 9 where I first went into the Cortex. [While] everyone was like [sighing], I was like, ‘Oh my God! We’re in the Cortex!’” he shares in the featurette.

But more than the fulfillment of his dreams as a fan, Felton said that his casting as Julian Albert has taught him a lot when it comes to acting on TV.

“I’ve learned so much here,” Felton told TVLine of his experience on the set of “The Flash.” “It’s quite a different skill set to be able to say, ‘Here’s a [movie] scene, and we’re going to spend all day doing the scene’ versus saying, ‘Here’s six scenes, every day for the next nine months or whatever.’ Making these scenes good, and under the very, very short amount of time space, is not something I was particularly used to, but working with the boys and girls here. … Obviously, they’re all so incredibly professional, so within 10 minutes of reading a scene off the page, it actually feels like a fully-flourished scene.”

Julian was last seen bidding farewell to Barry (Grant Gustin) a few moments before the Scarlet Speedster headed into the Speed Force in the Season 3 finale. Because Julian survived the season, it’s likely that Felton will remain a series regular in Season 4.

“The Flash” Season 4 premieres in the fall on The CW.