Throughout the series, Perry's office telephone # was Madison 5-1190; Della's was Hollywood 2-1799.
Walter Reed and John Pickard play detectives together here. They played G-men together in Government Agents vs Phantom Legion (1951).
When Perry Mason is summoned to the grand jury, there are only six jurors present. A grand jury will consist of 12 to 23 jurors. A petit jury can have as few as six jurors.
When Perry visits George Ballard, Ballard is listening to a radio show featuring folksy sportscaster "Red Walsh"-inspired by real life sportscaster Red Barber. Walsh predicts "the Beavers are a cinch to do it again this year". In 1957 the Oregon State Beavers did in fact repeat as Pacific Coast Conference football champions.
Mason calls his office from the Pool Room pay-phone, dialing the number 463-4811.