When McGarrett receives the taped message from the kidnappers, it is found on a very small reel that Danny puts on the tape recorder with a large take-up reel. As the tape plays, it is still a small reel. But when McGarrett stops the recorder, both reels are now large reels.
When McGarrett returns Timmy to Mr. Blake, he is wearing a light gray suit. But when he enters the house, he is seen in the darker suit that he wore earlier in the episode.
Geoffrey Thorpe, the actor who plays the kidnapped boy Timmy, also played a kidnapped boy (Scotty) in the Season Two episode "The Devil and Mr. Frog".
The official syndication number for this episode is 7006.