Musk tweeted the new footage over the weekend showing the 2-mile test tunnel in Hawthorne. The tunnel appeared nearly complete.
The system will use pods to move people or cars on electric platforms at speeds around 150-miles an hour.
An opening night event is set for Dec. 10 with free rides for the public the next day.
Musk has proposed a tunnel across western Los Angeles and another between a subway line and Dodger Stadium.
The Associated Press contributed to this report.