Emma Watson once confused Jimmy Fallon for Jimmy Kimmel

Late night television is good for so many things but it's especially great for embarrassing celebrities.

Jimmy Fallon, who currently hosts The Tonight Show, inadvertently left Emma Watson red faced years ago, but it was her own mistake that led to the embarrassing moment.

Appearing on last night's episode of Fallon's show, the Beauty and the Beast actress admitted she didn't want to come back on.

"Welcome back to our show, is it all flooding back to you?" he asked her.

"The trauma, the post-traumatic stress of my last performance on the Jimmy Fallon show," she admitted.

The two reminisced on Watson's last appearance on the show, which also happened to be the first time they'd met.

"Last time you were on the show, we just had met, and you couldn't be nicer and sweeter and gosh I'm a fan of yours," Fallon told her. "You came out and ... I gave you a compliment," he added.

And, before Fallon could launch into the interview, Watson interrupted him - and that's where everything went pear-shaped.

"Before you even start the interview, I just drove straight in there and said 'I love that Halloween candy thing that you do' and there was just silence," the actress remembered.

Fallon tried to fix the situation by being blasé, "the Halloween candy thing, is that right?" he told her. "That candy corn thing?"

But, Watson was keen to get her point across.

"No, when you get kids and you trick them," she said.

"And I said, that's Jimmy Kimmel - the first time we met," Fallon told her as the both of them burst out laughing.

While the two of them can laugh about it now, Watson revealed her confusion between Jimmy Kimmel Live and The Tonight Show with Jimmy Fallon was extremely traumatic.

"I died inside, turned bright red," she admitted.

And, if you're hoping to see the cringe-worthy exchange - you never will.

"You were so sweet because you could tell that I was dying inside and you said 'it's okay honey, if you want to go out and start again, we can do it again'" and that's exactly what she did.

"So I had you re-enter and then when you came and sat down I said, 'So are you a big fan of late night TV?'" Fallon said.

It turned out Watson's mistake worked in her favour because the redoing of the interview had "everyone in hysterics".