Ruby Rose's prank on co-star Nina Dobrev ended in tears after the Taylor Swift impersonator she'd hired injured herself.

While filming new action movie xXx: Return of Xander Cage, co-stars Ruby and Nina kept themselves entertained between takes by pulling elaborate pranks on each other.

But Nina has now revealed that one of Ruby's more complicated practical jokes unravelled before it even began.

"Ruby is friends with Taylor (Swift). So she (thought it would be fun) to hire an impersonator to come to our set, to sing for me and bombard me in my trailer," she said during an appearance on The Late Late Show with James Corden on Thursday night (19Jan17).

"But what she didn't know, was that the girl that was hired to do this, was actually a huge fan (of mine), so she got really nervous, and in the middle of it ended up hitting her head, and then started bleeding."

While that particular prank was a bit of a fail, Ruby had greater success with some of her other schemes.

On one occasion, the Australian star covered Nina's entire trailer with headshots of herself, and joked that The Vampire Diaries star was "obsessed" with her. To retaliate, Nina pulled out some water guns and blasted Ruby with water.

However, the 28-year-old admits that everyone on set eventually became exhausted by their antics.

"We had many, many, many pranks," she smiled. "By the end of it we were both terrified and didn't want to leave our trailers, we were quarantined in our trailers because we thought the other one was doing something and plotting against us, and we were absolutely right, because we were."