Jack says, "Well, you know you have to learn to trot before you can gallop... who said that?" This is a quote from John Ritter's late father, Tex Ritter.
The title of the pilot episode is "A Man About The House". This is in reference to the title of the UK comedy, "Man About The House", that "Three's Company" is based on. Similarly, the pilot episode of the UK sitcom was titled "Three's a Crowd", which is the name of the spin-off from Three's Company.
Chrissy (Suzanne Somers) is not portrayed as a "dumb blonde" or "airhead" as much during the first two seasons. Her makeup was more subtle and she had normal blonde hair. The character would become more dumb and ditzy during Season 3, when she had bleach blonde hair and started wearing more makeup.