Maguire, who played Spider-Man in three films between 2002 and 2007, was "intrigued immediately" by the possibility of returning to the role thanks to the filmmaker's "love and celebration" of the idea when they pitched him the concept.
"I just wanted to join that," Maguire, 46, said. "I'm a big fan of Tom and those movies and Andrew... It was really about getting together with these people and revisiting what was part of my history and getting a chance to come together."
For Garfield, the star of The Amazing Spider-Man and its 2014 sequel, he was likewise interested, but held out on committing until Maguire did so.
"If Tobey was going to do it, then I was like, 'Well, I have no choice,'" Garfield, 38, said. "I'd follow Tobey to the ends of the Earth."
After Maguire signed on, Garfield was pleased that the "intention" of his and the other actor's surprise appearance felt "very pure" and "like a great, creative idea, and a great, creative story."
"It wasn't like they were asking us to come and say hi and then leave again, but actually have our presence being in service to Tom," Garfield explained. "... I love the destiny feeling of the multiverse expanding in this film. And actually that without Tobey's Peter and Andrew's Peter being present for Tom's Peter at this very moment, he may not become the Peter Parker that he's supposed to become... I get chills thinking about it even now."
While Holland, 25, was thrilled to have the past Peter Parkers come on board, the idea of meeting them, he said, was "very daunting."
"The date of the other Spider-Mans are coming was etched on my calendar and I was getting closer, and closer, and closer. And the closer and closer I got, the more and more nervous I was," Holland admitted. "... At our first rehearsal, I had asked [co-stars] Jacob [Batalon] and Zendaya to come with me to just kind of be there as my support system."
Holland needn't have worried about hitting it off with Garfield and Maguire, though.
"As soon as I met you guys in Atlanta, I realized that I had nothing to be nervous about," he said. "... It was an amazing experience. From day one, it was a roller coaster that I didn't want to get off. It was a lot of fun... It was so collaborative, it was so playful. From [Andrew] cracking Tobey's back to [Andrew] coming up with the idea of pointing at us, it was all stuff that we came up with on the day, and it was just a lot of fun to be able to play with three guys in Spider-Man suits. It was a strange experience but one that I won't ever forget."
The experience was a great one for Garfield and Maguire too, with Garfield noting that "it exceeded my expectations."
"It was just kind of a joyful few weeks that we all got to spend together," Garfield said. "... I think it's a testament to these guys that it went the way it went, which was a brotherhood, which is beautiful."
"It was powerful for me to be working with Andrew and Tom, and powerful in a legitimately moving, emotional way," Maguire agreed. "... I was just grateful every day. Really, it was such a rich experience... the kind of sharing of something and the brotherhood of it. It was just so rich, emotional... It was pretty wild to witness the immensity of all of this history coming together and being put into this standalone, worthwhile story... I was really touched emotionally, but I also thought it had such a sweet elegance to it. That was so amazing."
Garfield was impressed by the film too, admitting he was "in pieces" after watching it for the first time.
"This is a deep movie. This isn't just fan service, which, you know, it partially is, but this is a movie that's about coming of age, acceptance of loss, acceptance of death, taking responsibility for your gifts," he said. "I was torn open by the journey that Tom went on... I think it's a beautiful film."
Holland, meanwhile, said he was thrilled with the fan reaction to Garfield and Maguire's appearance.
"One of my favorite things to do at the minute is to go online and watch fans react to you guys coming in that one scene in particular," he said. "I don't think I could ever imagine it being so well received by everyone... It feels like we've been on some really weird dream. It feels really strange."
As for if Holland's third Spider-Man flick will be his last, the actor said that the answer to that is still unclear.
"This film for me was as special as an experience could ever be. Sharing the screen with these guys... it’s been such a wonderful experience, of which I have such amazing memories," he said. "I don’t know. There's part of me that feels like it's the perfect time to jump off the building and swing off into the sunset and let the next lucky young kid come in to don the suit."
"I know I love this character, and I know that I am not ready to say goodbye," Holland continued, "but if it’s time for me to say goodbye, then I will do so proudly, knowing that I’ve achieved everything I wanted to with this character, and sharing it with these boys will be forever one of the most special experiences of my career."
Earlier this month, Garfield gushed to ET about teaming up with the two other Peter Parkers for Spider-Man: No Way Home.
"The fact that I get to be one of those people wearing the suit next to my actual Spider-Man hero, Tobey Maguire, and the brilliant, incredibly talented, heartfelt, funny, good, sweet, perfect Spider-Man of Tom Holland, and I get to be the middle brother, and I get to be in awe of my older brother and in full longing to protect my younger brother," he said. "And also, there's something spiritual that kind of happened and happens... [when] these three guys, who maybe felt very lonely in the universe before, suddenly are aware that they're never alone, they never have been alone and actually there is a brotherhood out there, and God knows how many more Spider-Men, Peter Parkers, there are out there to share in that support group with."