John Carmack has always tried to code engines without using patented software. When he released the Doom source code, he had to exclude a licensed library, which he called a mistake. Doom 3 had a similar problem with the shadowing algorithm, but it was quite easy for him to fix it in the GPL release.
It appears that RAGE is using Bink video, which is another licensed encoding for videos. I don't know if anything besides Bink is used (Steamworks libraries on Windows?). What does this mean for the future of Id Tech 5?

I don't know how it is now, but the encoding tools used to be freely available from the Bink site when they first entered the scene. Just looking at their site it still seems to be the case, you just won't get the full SDK or license for commercial use.

Yes the encoding tools are still freely available for RAD Game Tools Bink format.
I guess they'll just have to cut it from the source code for RAGE though if they publish it, just like they'll probably just have to scrap the code for the HD Photo / JPEG-XR texture compression they licensed.

Intriguing. Have a source?

Source? Huh no, that was just my guess - it's what I would've done. Simply cut those lines of code out, and leave a friendly note explaining why et.c.

Bink video should fall under the system library exception - GPL 2 is quite woolly on this (the intention is clear but the wording is open to interpretation), but GPL 3 (which recent source releases have been using) is much more solid.