The Tim and Martin O'Hara Residence on "My Favorite Martian"

There were some changes made to the set in the color photos when the show changed studios for its third season. 

My Favorite Martian Exterior Set

Martin and Tim lived in the apartment over Mrs. Brown's garage.

These "exteriors" are clearly filmed inside a soundstage! You can some differences in the set (by their front door) in the color photos when the show changed studios for its third season. 

Jello Molds on Kitchen Walls

My Three Sons 1971

My Favorite Martian 1964

Ozzie & Harriet 1959

Hazel 1965

Here's Lucy 1968

Dick Van Dyke Show 1964

Mister Ed 1963 

Petticoat Junction 1966