Harrison also recently said fans will experience a "wild ride" watching Colton's journey to find lasting love unfold on television and the conclusion of Season 23 will arguably be the most dramatic one yet.
"The other thing you need to remember is what happened with [Arie Luyendyk Jr.] -- this continues airing until the end of March, so I would say the ending is not written," Mills said, referencing how Arie did not find true love until after Season 22 wrapped filming.
Shortly after getting engaged to Becca Kufrin, Arie realized he was still in love with his runner-up, Lauren Burnham. He therefore dumped Becca after several weeks together in early January and begged Lauren to take him back.
Thankfully, things worked out for the pro racing driver and now he's expecting his first child with Lauren, whom he marries on January 12 in Hawaii.
"What we learned with Arie and Becca is that we will continue filming regardless [after Colton picks a winner]," Mills told Variety.
Regardless of whether Colton found the woman of his dreams or got his heart broken, Mills noted producers were "absolutely" pleased with their decision to cast him as the Bachelor instead of frontrunners Jason Tartick and Blake Horstmann.
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"[But] do I think I would have been pleased with the other ones? Absolutely. At this point last year with Arie, I would have said, 'Yeah, it's a solid season.' We never would have known what would have happened with Becca until about three weeks into the run of the show," Mills reasoned.
"But at this point now, we're absolutely thrilled."
Harrison recently told Entertainment Tonight Colton's season will have a very "organic feel" and not seem "very produced" because Colton pushed back on producers, forcing them to go with the flow and follow his lead.