Trouble in paradise? Nope. The kiss was part of Cyrus' Oct. 18 guest stint on the sitcom as Missi, the quirky, chatty daughter of Walden's (Ashton Kutcher's) old friend and a love interest for Jake (Jones).
In the first of the starlet's two episodes on the show, Missi sat on a beach with Jake, who had just come back from the military, and gabbed incessantly until he quieted her with an unexpected smooch.
Filming the kissing scenes with the 19-year-old Jones, Cyrus said, was a little awkward at first.
"The prop guys would always [ask], 'Do you have your [engagement] ring on?' and I'd be like, 'I have to take my ring off to make out with Angus? This is creepy!'" the starlet told Jay Leno earlier this month.
Hemsworth, 22, need not worry, though. Calling in to On Air With Ryan Seacrest Thursday, the former Hannah Montana star told the host that she and her fiance, whom she met on the set of the film The Last Song, are totally secure in their relationship. Both know -- and accept -- that they'll occasionally have to kiss other people onscreen.
"At this point we're engaged, like we’re forever. I think if I was a girlfriend...I would feel like I need to show my ownership," Cyrus said, adding that in the past she had "turned down scripts because...I don't think any career is worth stressing out the person that you love the most or making them feel hurt."
That's not a problem in her current relationship, she insisted. "We give each other boundaries."