When Tom explains to John that Lorna was kidnapped and is not a true Doone, the girl playing young Lorna changes. The girl in the stage coach has blonde hair, but the girl put on the horse with Sir Ensor Doone has brown hair.
When Lorna has to leave the Ridd farm after her parentage is discovered, and she is saying goodbye to John, there is a strand of her hair that differs in position from close-up to long shot. In the close ups, it is tucked behind her ear; in the long shot, it is hanging loose at the side of her face.
When John shows Uncle Rueben Huckaback the secret way through the rocks into Doone valley, it is pouring with rain and both are drenched. When John climbs through the rocks and enters the valley, not only has it stopped raining but his clothing and hair are completely dry.