Currently in Australia to film The Rover, Rob was biking around the 'burbs when fans snapped his photo. Unfortunately for the Twilight star, the picture ended up in the hands of eagle-eyed officers who gave him a warning.
According to a statement by the South Australian police given to UK site The Metro, "He will not be fined, it is just a simple caution. We had a chat with him and told him that it is a requirement to wear a helmet while cycling a pushbike. It's no biggie", said the police spokesman.
"Someone took a picture of him when he was out cycling so that is how we knew. If he does it again he will be fined," the spokesperson warned.
Lesson learned: protect that melon, Rob!
The Rover, directed by Animal Kingdom director David Michod, is a Western set in a near-future Australia and also stars Guy Pearce.