Why is everyone so hung up on the term "Release Candidate" vs Beta. RC is just a fancy way of saying it is a Beta that they think they can release. It doesn't really change anything, they still test the RC the same way they test the betas, they just believe its farther along then they had expected. Just like Beta's there can be multiple iterations of Release Candidates. I think what was most interesting about Elon's comments on the subject was the fact that the Release Candidates we see in the wild today were mostly made on the production line and not mostly made by hand. I think that is what is significant about these cars that makes them something a bit more then a beta. This is a good thing, because it means that they can focus on finding issues while testing cars that are closer to production and that moving from hand built beta cars to the production line does not expose new issues related to the production line vs being hand built as they bypassed the purely beta stage. This does not mean they wont be testing as much as possible. In fact, it could mean a lot more testing because they can product more test cars, faster, because they are using a production line to do so. There is no value in a pure beta stage with hand built cars when you can use cars off the production line and find issues that will actually impact production, since the cars will not be hand built int the future.
As many have stated, building cars with thousands of parts many of which never existed before this process, is a difficult task and issues come up. There are no FWD to screw things up. The car is simpler then the S and vastly simpler than the X. They have more engineer talent then they ever had and they will figure it out. I am sure there are dozens of instances where what the original poster is alluding to that his source doesn't know about. This stuff is not easy. This is a big reason why many old school automakers expected Tesla to fail long ago. These guys land rockets that went to space then relaunch them. They will figure this out. Have faith.