The watch said 120 a second or two earlier. If I was just looking at the CGMS, it's not so obvious that there's a problem. On the other hand, the watch is telling me that I'm probably 80 at this moment (and dropping like a rock). Explanation of the display, the number to the far right is telling me number of minutes estimated until I'm 80, if the arrow was pointing up, that would indicate number of minutes until I'm 180.
This is a real example of how some background calculations can cut through allot of noise. 10+ minute delay, device inaccuracy and calibration inaccuracy combined can't hide the fact that a plummeting blood sugar is going to get you into the danger zone quicker than you realize.
Next time, more fun with hardware.