Fred's car changes from right hand drive (steering wheel on the right) earlier in the show to left hand drive (steering wheel on the left) later. This is especially evident with Barney in the passenger seat.
Wilma and Barney move their game pieces in opposite directions on the Rockopoly game board.
The Flintstones have a garden hose to water their flowers but Fred has to use an elephant's trunk full of water to take a shower.