As requested, Fritz brings Sarah Dacos a Sidecar. A Sidecar is a drink made with fresh squeezed lemon juice, Cointreau, and cognac or brandy, resulting in a very pale yellow drink. The Sidecar Fritz serves Sarah is dark brown, not pale yellow.
When Wragg takes out the bullet that was found in Althaus's apartment it has no rifling marks on it, indicating that it had never been fired. Thus it would be impossible to compare it to bullets fired from the gun thought to be the murder weapon.
As all fans of the "Nero Wolfe" novels know, Wolfe never discusses a case at the dinner table, yet the discussion with Lon Cohen about Mrs. Bruner takes place there. In the book it takes place in Wolfe's office, but the writers needed to show both the dinner and the discussion so they combined them for their convenience.
During the briefing to the actors in the basement, Wolfe says "You'll be in this house 18 hours." It's suppose to be 28 hours (as stated in the novel) which Archie confirms when after the briefing his voice over says "I wouldn't want to go through that 28 hours again."
Set in the 1950s, but characters give telephone numbers as seven digits. This was never done at that time, numbers were always read as an Exchange (Plaza, Greenwich), followed by five digits, such as "Plaza 5-2222".
Though the series was set in the 1950's, the book around which the case revolves, "The FBI Nobody Knows" by Fred Cook, was actually published in 1964.