While Slip & Frag is currently in a fully playable state, and even allows for some experimentation with modifications such as new maps created by the Quake user community, users might anyway have some questions about the usage of the game engine, and some could even have stumbled upon game failures or crashes that they wish to report.
Check this wiki if you need answers for some of your questions. I will try to have it updated as frequently as possible.
An issue tracker for Slip & Frag has been enabled, and it is available here.
Source code for the engine is available here as well - the original Quake engine is, after all, available under the terms of the GNU General Public License, version 2.0.
Finally, if everything else fails, feel free to drop me a line.