Trivia: A clever, subtle hint as to Mason's guilt - Columbo arrives at the animal pound just in time to stop him feeding Laurel and Hardy (the dogs he trained to kill on command) a large amount of chocolate treats. He has planned this murder meticulously, and he would be aware that chocolate is extremely toxic to dogs. The amount he is planning to feed them from the bulging bag of large chocolate balls he is holding would kill both dogs within hours if ingested.
Trivia: The show featured the first toilet flush heard on TV.