The Night of the Circus of Death - S3-E9
Factual error: At the mint, Arte hides in a broom closet. He carries nothing in (nor did he hide anything in there beforehand), yet he emerges later in an "old man" disguise, wearing a wig, hat, mustache, false nose, glasses and janitor costume. Magic closet? (00:35:00)
The Night of the Circus of Death - S3-E9
Continuity mistake: The draperies are fully engulfed in flames when the murderer runs through them and out onto the balcony. Cut to an exterior shot as he escapes, and the window dressings are perfectly intact with no sign of the fire. (00:03:10)
The Night of the Circus of Death - S3-E9
Visible crew/equipment: While West and Gordon question Mr. Lennox at the Denver Mint, the boom shadow can be seen moving at the upper left of the frame. (00:30:15)
The Night of the Circus of Death - S3-E9
Revealing mistake: The single kerosene lamp West lights inside Bronzini's circus wagon not only lights up the entire room, it also impossibly casts his shadow on two different walls at once as he searches the various trunks. (00:14:50)