This season was filmed entirely in black and white. The overall tone was more straight sci-fi than that of subsequent seasons. There were some fantasy elements that crept in. Dr. Smith and the robot started out as villains. The Robot quickly became more of a lovable character. Dr. Smith still was the villain, but instead of being cold, he became more comedicly villainous. Instead of being vicious, he was just lazy, greedy, shiftless, untrustworthy, etc. The theme song for this season was composed by John Williams.
"No Place to Hide" is not part of the series continuity. Though not technically a first season episode, it was later recycled by Irwin Allen and parts of it were used in the first five aired episodes.
Starting during episode 3, "Island in the Sky", every episode this season is spent on the planet Preplanis.