Hyperloop claims:

“Hyperloop is also unique in that it is an open design concept, similar to Linux. […] The intent of this document has been to create a new open source form of transportation that could revolutionize travel. The authors welcome feedback and will incorporate it into future revisions of the Hyperloop project, following other open source models such as Linux.”

but it is not actually open source. The PDF itself has no copyright notice, so it falls under the licensing terms of the main Tesla website, which clearly say:

“The text, images, graphics, sound files, animation files, video files and their arrangement on Tesla Motors, Inc. internet sites are all subject to copyright and other intellectual property protection. These objects may not be copied for commercial use or distribution, nor may these objects be modified or reposted. […] Accordingly, please be on notice that neither these internet sites, nor any material contained therein shall in any way grant or be taken to grant any person a license to Tesla Motors, Inc.’s intellectual property.”

In other words, anyone who modifies the Hyperloop design, or reposts it on their blog, is committing copyright infringement. (I claim these short quotes as ‘fair use’.)

The document also doesn’t include any actual “source” (details of how the document was created); eg. the names of anyone who worked on it with Elon, the cost calculation methods, and the software used to create the diagrams are all kept secret. This means that modifying it, the raison d’etre of open source projects, is made impractical as well as illegal. Yes, the words “open source” sound cool and all, but saying it does not make it so.