I was contacted by a SpaceX recruiter on LinkedIn and flown to LA. You're in for a treat.
First, there's a tour of the factory, which is awesome. You'll give a 30-minute to 1-hour presentation to a group of engineers and managers. Then, you'll break off into approximately 30-minute one-on-one interviews. If you do well on the presentation, you're in for an experience of a lifetime (if you like rockets, like me). Either way, stick to the basics and know your fundamentals. Be prepared to strut your stuff too. Time flies when you're having fun!
My advice to any new graduates looking for their first job: Think about what type of lifestyle will make you the happiest. SpaceX is awesome, but it's not the right fit for everyone! Just be sure to chat with your hiring manager after the interview and manage expectations. Great communication is the key to many fun things in life, like Rocket League ;)
I won't spoil the fun.
Know your MechE basics.
The more you show during the presentation, the more fun the interview will be later on.
My last piece of advice is...
The following metrics were computed from 146 interview experiences for the SpaceX Mechanical Engineer role in United States.
SpaceX's interview process for their Mechanical Engineer roles in the United States is extremely selective, failing the vast majority of engineers.
Candidates reported having very good feelings for SpaceX's Mechanical Engineer interview process in United States.