"She obviously didn't know I had a crush on her either," Reeves says after seeing the clip.
When DeGeneres marvels that they were both harboring crushes on each other and questions why they never dated, Reeves exclaims, "We were working!"
Though they never got together, they have remained friends, even starring alongside each other again in 2006's The Lake House. "It was nice to go to work," he says. "She's a wonderful person."
Bullock first admitted her crush on Reeves during a December episode of Ellen, even pointing to Reeves as the best part of filming the action flick.
"I think about how sweet Keanu Reeves was and how handsome he was," she gushed. "It was hard. It was really hard for me to really be serious. He'd look at me and I'd [giggle]."
Bullock, 54, even gave her crush an all-important job during the film's stunts.
"My dress sort of kept flying up and I said, 'Whatever you do, just keep my dress down,'" she recalled. "The whole stunt he just made sure my dress [stayed down]. It was very sweet."
ET recently caught up with Reeves at the premiere of his latest flick, John Wick: Chapter 3 -- Parabellum, where he spoke about making Speed, which will celebrate its 25th anniversary next month.
"It was a great experience to make that film. [I] got to meet Sandra Bullock, got to work with her, it was fantastic," he said. "It was a great role. Point Break was really a big break for me in action films and Speed was the second one and a chance to do as much action as I could. With the help and support of all the stunt people and everything, that film was a lot of fun to do."
As for his favorite memories on the Speed set with Bullock, who plays his love interest in the movie, Reeves recalled, "It was just her talent in all of the environments. We had to pretend some pretty wacky stuff and she was so authentic and her humor and intelligence, authenticity. It was just a joy to be around and to perform with."
John Wick: Chapter 3 -- Parabellum is now playing in theaters.