Pat Morita who played Arnold signed his contract pick-up option to continue for another 2 or 3 seasons, however soon after signing he was offered his own TV series and was allowed to leave Happy Days. The 1976 TV series that developed was "Mr. T and Tina" which aired only 5 episodes (another 5 episodes were never aired).
The restrooms at Arnold's restaurant have the Men's room on the left, and the Lady's room on the right. But, in all of the shots of the guys coming into the restroom, they walk in making an immediate right.