"I wouldn't count the George Melies bullet in the moon because that had cartoonlike proportions because the actual bullet was only a little taller than the passengers standing inside it. "Lost in Space"'s Jupiter was only about the size of a large room. "

The main control room was, but the outer hull blueprints show "rooms" where items like the chariot parts and space pod were stored.

Watch the shows with people walking around the ship, or the episode where they show the full sized mockup, and you'll see it's MUCH larger then just one room.. tit was 2-3 stories tall, and then add the circumference as well.

But the main point of this, is that it was tiny being swallowed by the alien ship, so that ship would have been 30-50 stories tall, and a 7-8 hundered stories in length.

 

Way too many people take way too many things way too seriously.