There's a worry Tesla is hiding softening sales. They had the capacity to produce 7150 cars this quarter but only sold 5550, a difference of 1650. Some of those cars are en route to Europe, but still, the number seems high. Talking about producing vehicles for internal use and marketing purposes, along with increased investment in new models and versions, can be interpreted as "our U.S. sales are softening unexpectedly." However, it does seem a stretch to draw those kinds of conclusions.
Musk specifically covered this in the earnings call. They are production constrained and had to hold back deliveries in the US to ensure that people who made reservations in Europe two years ago would get their car.
According to the summary I've seen[1] he said they were constrained by the available supply of batteries. Now, Musk spun this as a temporary setback, but one of the most widely-reported potential issues they have is that the number of batteries they need is huge. As in, if they expand much they'd require the entire current global production of 18650 cells[2] - and that's just to produce 40,000 cars a year!
Something doesn't add up then: if Tesla can produce 7150 cars per quarter, why is next quarter guidance only for 5K cars sold? Another new market with long lead times?
Tesla can't produce 7150 cars per quarter as of today, the production capacity as of Q3 end was probably on the order of 6200 cars/quarter. The reason guidance is lower than this, is that the company is expanding to many foreign markets and hence many cars are in transit.
This was also covered on the earnings call. Tesla is currently shipping to Europe and will if I remember correctly start shipping to China during Q4. Remember, shipping cars takes time since they need to go on freight ships.