Here's the opening graph from the Motley Fool's write-up on the tour:

"If you're looking for a glimpse into the bread and butter of Tesla Motors' business, a tour of the electric-car maker's 5.3 million square-foot factory will do the trick."

The visit occurred on August 31st and here's a condensed form of the highlights (see source article for more details):

A rapidly growing company

"Factory changes in the past year-and-a-half revealed a rapidly growing company. The upgrade was most evident in the scale of the new second body assembly line, where an army of recent red robot-arm recruits moved around to perform up to five tasks each. A whopping 580 robots on the body line are building Tesla's Model X SUV…"

Tesla Factory Model X General Assembly

"…my third-quarter factory visit didn't show signs of Model X production challenges. On the contrary, the company's general assembly line, which is shared by the Model S and Model X, and doesn't batch vehicle models in any particular order, easily had just as many Model X vehicles on the line as it did Model S."

The missing piece

"Before Tesla started building its second body assembly line, you could seemingly drive a golf cart around near-empty parts of the factory for minutes at a time. Now the company is using all of the factory's space, albeit much of it simply for temporary warehousing."