The voice of the strangler is Biff from Back To The Future.
'SpongeBob Meets the Strangler' is set on July 14th which is SpongeBob's birthday which explains the party that is thrown for him.
The is the last episode where SpongeBob uses Mr. Whiskers voice.
One of the gag items Frank sells is a gag dollar however selling counterfeit money is a federal offense though this was merely done for comedic effect.
This is the last episode that premiered before the release of The SpongeBob SquarePants Movie (2004)