Eyewitness News has confirmed that Burkhart took the device out to walk through a metal detector, and he retrieved it when he left.
A security guard noticed and took a picture of the object. The guard's photograph could end up being a key piece of evidence in court.
Meanwhile, Burkhart's mother was in court on Wednesday.
Dorothee Burkhart came to the defense of her son, but was eventually removed from the courtroom after continued outbursts.
During her appearance, she agreed to accept a court-appointed attorney, meaning the formal extradition process can finally get under way. She is wanted on fraud charges in Germany.
Her son is accused of setting dozens of fires that terrorized Los Angeles over New Year's weekend.
Dorothee Burkhart claims her son is mentally ill and not capable of setting the fires.
She was ordered held without bail and will be back in federal court Jan. 25.
Her son is expected in L.A. County Superior Court on Jan. 24 for arraignemnt on 37 counts of arson. He is being held on $2.8 million.
See photos of the fire damage in Hollywood and North Hollywood.
