The Tears of Uther Pendragon: Part Two - S3-E2
Visible crew/equipment: When Morgana is hiding from Gaius there is a mic peeking out of the corner of the bed in the lower left corner.
Merlin (2008)
1 visible crew/equipment mistake in season 3 - chronological order
Starring: John Hurt, Richard Wilson, Colin Morgan, Bradley James
Factual error: In the show Gaius wears glasses, except eyeglasses first came into use in the late 13th century while the legend of King Arthur is around the 5th or 6th century.