Joseph Kearns, the grandfatherly neighbor Mr George Wilson, was just 10 years older than the biological father of Jay North, who played Dennis Mitchell.
Good ol' Mr. Wilson!
The side of the Wilsons' house closest to the Mitchell residence has an architectural inconsistency between front and back views. When viewed from Elm Street, the Mitchells' driveway appears to directly border the outside wall of the Wilsons' living room. However, in all but season 2, there is a door in the living room that exits toward the Mitchell residence. Beyond that door is a fence, sometimes with a gate that exits into the corner of the Wilsons' front yard. Viewed from the front, that gate could not exist. It would come out into the corner of the Wilsons' yard where the front yard, living room and fence meet the edge of the Mitchells' driveway.