This was by far the highest-rated episode of the series, going up against two low-rated specials.
Although clearly seen in the role of 'Dottie Lomax,' actress Jackie Russell is billed in the closing credits as playing 'Virginia.'
At 9:32 Ellery says "...we'll be there in 20 minutes...". In every episode when one of the Queens tells someone they are on their way, they almost always state that they'll be there in 20 minutes. Given the traffic in Manhattan and the other boroughs, that's a remarkably consistent drive time between any two locations in New York City.
Dottie Lomax's last known address is given as "457 Bleecker Street". Like most addresses in television programs set in Manhattan, this is fictitious. Bleecker Street addresses (which run from southeast to northwest from the Bowery to Hudson Street) end in the 420s; if such an address existed, it would most likely be on the site of Abingdon Square Park in the West Village.
Leo states that it has been four months since the St. Patrick's Day murderer, placing this story in July 1947. Curiously, the previous episode, The Adventure of the Eccentric Engineer (1976), cannot take place before October 1947, as the musical High Button Shoes, which three characters in that episode attend, did not open until then.