Full stop or comma?

There was a cracking by-line in today's paper Metro, which is unfortunately not in the corresponding online article. Under a picture of the spaceport was the caption:

"The spaceport will be dug into the New Mexico desert, where it will harness natural resources and be ecologically sound. Apart from the space travel bit, of course".

The incorrect use of a full stop rather than a comma before the word "Apart" makes it all the funnier. Of course.