If you're living in the confines of the universe of The Room, then this is what we know:
-Denny had drug dealings with Chris-R.
-We don't know if Denny was "giving them, selling them"
-Denny owed Chris-R money, but Chris-R was in a rush and was unable to wait 5 minutes for the money to arrive. Though Denny seemed surprised that Chris-R showed up, so how did he arrange for the money to show up in "5 minutes"
-Chris-R carried a concealed gun. However, it appears the gun is fake, so threating Denny with it and carrying it probably isn't that serious of an issue even though he is using the fake gun in a threatening manner in order to acquire money from Denny.
-Speaking of Denny, if Chris-R is going to jail then Denny should most likely being going down with him.
-Denny is rescued by everybody else in the movie and Mark and Johnny wrestle the gun away from Chris-R (probably not the smartest idea) and take him downstairs. When they return they assure Denny that Chris-R is going to jail. Luckily, the police and a judge were standing by downstairs ready to wrap the case up.
In Johnnys universe:
The cops and judge say "Let's go to jail, hahh?" and Chris-R gets a maximum sentence of consecutive life sentences. Denny gets in no trouble for his involvement for drug dealing, drops the habit quick, and marries Elizabeth.
In the real universe:
There's no real hard evidence against Chris-R and in all likelihood what happened was that Johnny takes Chris-R downstairs and says "Okay, you've been bad. You need to go to the police station now and turn yourself into prison." and Chris-R walks away confused.