When Mike explains the meaning of the name "Yutahay Flats" to Alice, she replies, "That'll come in handy if we run into Tonto". In part 3, they meet Chief Eagle Cloud, played by Jay Silverheels, who played Tonto in The Lone Ranger (1949).
Jim Backus played the identical character down to the costume and set on an episode of Gillian's Island. It was a dream sequence where everyone was trying to kill Emily the duck.
Although Welcome Aboard (1974) makes it definitively clear that the Bradys live in Los Angeles, there's another clue here. As the family stands admiring the sunrise and the clean air, Greg says "I'll bet our lungs are wondering what happened to all the smog!" (LA's smog was legendary at the time this show was in production.)
First episode where no scenes took place at the Brady house.
The shot of the family admiring the canyon from the overlook was filmed at the same time as a similar scene in The Brady Braves (1971), as they're leaving the Grand Canyon. You can tell because all of their outfits are exactly the same.