The Twilight actor was filming a scene with Kristen Stewart's stunt woman when the accident happened.
Robert told MyParkMag: "The scariest stunt was when I run and I put my hand out to stop this car which is racing towards me.
"I had practiced it a bunch of times but the car is like coming at 30 miles per hour. And I was sick on the day of shooting.
"I had taken antibiotics and I was really dozy and the car went off its tracks. So there I am, holding Kristen's stunt double and my timing was off because I wasn't feeling too good and the car like hit me in the face. Then I dropped her and I couldn't stop laughing.
"I didn't have any injuries but Kristen's double could barely walk for a like a month. I felt so bad!!"
Robert's fans will be glad that their favourite actor wasn't injured and will be starring in the next two Twilight movies.
Rob isn't the only actor to experience stunts going wrong recently.
Shia LaBeouf was injured while filming Transformers 2 when shrapnel from an explosion cut his eyelid.