Quick Millions (1939)

Returing home from their trip to Hollywood, John Jones gets a telegram that he has been left a gold mine by his uncle in Arizona. The family loads up their automobile and heads for Arizona. THe family arrives at the old mine but are unaware that a gang of bank robbers are hiding in a concealed cellar in the mine. A member of the gang, posing as a geologist, convinces Mr. Jones that there is no gold in the mine (and there really isn't) but one of the Jones' boys finds a nugget (that had fallen off of a watch chain)and that leads to complications, including Mr. Jones being jailed mistakenly as a member of the bank-robbing gang.