Interesting trivia? I never knew the robot had designation as such so went looking..
The robot identified itself as such in episode S02E03 "The Ghost Planet".
When asked to identify itself by the Supreme Prototype, the robot responded with his full model and assignment:
LEADER: Identify yourself.
WILL: I'm Will Robinson.
LEADER: Silence! Only the robot. The Earth creature will remain at attention.
LEADER: Repeat. Identify yourself.
B-9: Robot, model B-9, designed and computerized as a mechanized electronic aid for Earth voyagers engaged in astral expeditions.
As far as I know, this is the only time the name "B-9" was ever actually used on-screen. It quickly stuck with fans, however, and the robot has been known as B-9 ever since.
Interestingly too, here's the connection to another classic robot from the 1956 sci-fi movie classic Forbidden Planet named Robby the Robot. Surely you must have seen the movie.
Yeah, I've watched it.
I enjoyed it, fore sure. Not the best thing on telly, but most definitely not the worst either.
Parker Posey's take on Dr. Smith is definitely a standout of the show, and she makes the character enjoyably dislikeable.
She's a sociopathic, narcissistic grifter, and the performance is as much about her body language as it is about the character's actions. Wild hair, a vicious slash of a mouth, nervously darting eyes and her unrestrained, unjustifiably confident posture all serve to make the character eminently untrustable.