The calendar on the wall of the police detective's office is an actual April 1954 calendar that shows the first day of the month falling on a Thursday and the last day of the month falling on a Friday. This wall calendar can be seen out of focus during a time when Webb's monologue voice over claims was "Saturday, April 23" and again in focus on "Monday, April 25." However, the authentic calendar on the wall is a day off from Webb's claims with Saturday being April 24 and Monday falling on April 26.
The update about the streets not intersecting in real life comes under the heading of "names were changed to protect the innocent". Webb did this many times in the TV series as well as in this picture.