The incident occurred just after 5 PM when a plane carrying the two actors, who were attending a private event at the popular historic monument, landed safely at the estate's private landing strip.
San Luis Obispo Sheriff's Department PIO Rob Bryn told Access the pilot did not set the plane's parking brake and the Cessna 421B plane rolled into a parked rental car while Brooke and Jim were still on the plane.
"No one was ever in any danger," Officer Bryn told Access.
The parked car sustained the majority of the damage.
Though the incident was minor, Bryn said the NTSB was notified of the incident, which is required when any aircraft is involved in an accident.
Related Content from AccessHollywood.com:
VIEW THE PHOTOS: Brooke Shields
PLAY IT NOW: Was Brooke Shields' Mother Checked Out Of Facility By Tabloid Reporters?
PLAY IT NOW: How Did Brooke Shields Save Robert Pattinson?