Bonanza/YMMV

Franchise Zombie: In the final season after Dan Blocker's death which featured only Lorne Greene and Michael Landon out of the original cast.
Germans Love David Hasselhoff: Bonanza was aired in Poland during The Sixties (or was it The Seventies?...), when people desperately craved anything other than the official propaganda. This was said to result in almost total depopulation of streets around the time of airing. And it can't be wholly dismissed as Nostalgia Filter.
Special Effects Failure: There's an episodes where some bandits use dynamite to blow open the safe at the bank. It looks like they just stuck a sparkler on it and rigged the door to fall down.
Replacement Scrappy: The fourth Cartwright son, Jamie, who was adopted some time after Adam's departure.