"There definitely was a time I thought that the show might not come back," Harrison, 47, told ET about Bachelor in Paradise, which will premiere its fifth season on ABC next week.
"I mean any show, as we just learned in recent history, you are one catastrophic event away from being gone. I always understood that about this business, and were all tenuous at best, we're all replaceable, and that television, that this business, it's a crazy, crazy business."
As a result, Harrison said he "couldn't be more grateful" the spinoff will continue to air and entertain Bachelor Nation.
While Warner Bros. was conducting an investigation into the events that transpired at Playa Escondida in Mexico, Corinne called herself a traumatized "victim" through a press statement, which prompted speculation DeMario had sexually assaulted Corinne.
DeMario, however, argued at the time that his character had been "assassinated" with "false claims and malicious allegations." (Corinne later clarified she felt victimized by the press as well as people with judgments and assumptions about the scandal, not DeMario).
Warner Bros. ultimately determined in its investigation there was no evidence of misconduct or wrongdoing on the set of Bachelor in Paradise, and so the show resumed filming in late June and eventually aired the rest of the season. In addition, DeMario's name was cleared.
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"It's never lost on me that something like last summer could be bigger than it was," Harrison told ET.
"Luckily, we have some great people at the helm and we dove in, myself included, got our hands dirty and fixed it and solved the problem and everybody came back. It goes, I think, a long way in showing how everyone trust and love us that they come back and they believe this can work."
Part of fixing the problem included enforcing a "two drink per hour maximum" for each bachelor or bachelorette at the Mexican resort in order to avoid drunken encounters and misunderstandings.
"I mean, as soon as we got back last summer, I was like, 'Okay, what's the dynamic going to be?' And everybody got right back to it, and I'm like, 'We're fine,'" Harrison added.
Harrison said it's important for production to make sure everybody is safe and feeling comfortable on the set of their ABC reality dating series.
While they wanted the cast to have "a good time" they needed to make sure it's "the right kind of good time."
"[The kind of time] where everybody is in on it and in on the joke and knows what's happening," Harrison explained.
"But Bachelor in Paradise is always about fun, because it's not The Bachelor and Bachelorette, you all sign back up for this, it's like summer camp. It's all the people you know and love -- and some you don't know or love them as much -- but it's about having a good time."