I noticed this as well. What is more interesting is that I have an intersection that consists of a T junction for three of the four roads, and the fourth road is a 45-degree angle. Traffic coming from the 45 degree angle road going "straight" have a right-turn arrow on the road, but one that is not as sharp as the regular right turn..... but the system counts that as a right turn, so the traffic coming from that road continuedly flows straight with a green light with the option "turn on red" turned on.
I'm not near my gaming rig atm, so I quick and dirty paint job to illustrate: (Paint skills: 2 out of 5 stars)
Traffic marked in green are BOTH considered a "right on red", which should not be the case.....