The quicksand scene is shot in the same forested area as the opening credits of the Andy Griffith Show.
Last show of the series.
The scenes with Mark (Johnny Crawford) and Lorrie (Karen Sue Trent) were filmed at Franklin Canyon Reservoir or Myers Lake as it's known to fans of The Andy Griffith Show.
The song Mark sang and which was used as the background music is "Greensleeves" which was the basis of the Christmas Carol "What Child Is This".