Although the Brady household has two telephones, in later seasons the phone in Mike's office/den appears in the living room, near the front door. The other phone stays in the same location on the family room counter until A Very Brady Christmas (1988) and the Brady Bunch spin-offs, when it becomes a push-button phone mounted on the wall.
On the phone, Jan tells her friend, "I don't see what's wrong with freckles! I got lots of 'em!" In The Not-So-Ugly Duckling (1970) the following season, Jan rubs lemon juice on her freckles to try to get rid of them.
The title is a reference to the phrase, "Sorry, wrong number."
The phone bill that shocked Mike, Carol and Alice was under $36, given their later conversation. That would come to about $320 in 2025.