Oh, My Aching Antenna - S1-E33
Continuity mistake: Even though Tim and Uncle Martin live on the 2nd floor at Mrs. Brown's above the garage, every view outside the living room window with the sheer drapes shows the house across the street from a ground floor perspective. This happens in multiple episodes.
The Cousins - S1-E37
Continuity mistake: When Mr. Castle complains that Martin Lane is a traitor, his secretary reminds him that he has declared Martin to be "the best managing editor in the country." Mr. Castle then takes a seat while holding his newspaper, but in the next shot his hands are empty as he impatiently stands up.