Recently, as the interest in cannabidiol (CBD) has grown due to its therapeutic potential, e-cigarette liquids containing CBD have proliferated on the market. Typically, e-liquids contain variable concentrations of CBD (from 2 mg∙mL−1 to 20 mg∙mL−1) in propylene glycol or 70:30 propylene glycol:glycerol mixture and are eventually flavored with food-grade flavors. In this work, carried out by a GC-MS analysis of the condensed smoke produced by a real e-cig, we have demonstrated the actual amount of CBD that can survive the smoking process, and we found that negligible amounts of THCs are formed during the smoking process (i.e., the amount formed was <0.005 mg for each mg of vaped CBD); considering that the threshold dose for ∆9-THC is around 2.5 mg (smoked or ingested per os), it is reasonable to conclude that accidental THC intoxication is unlikely, which is a very important issue from a forensic point of view, as in some court cases the use of e-cig liquids containing CBD has been argued as being the source of THC intoxication. Furthermore, all the other cannabinoids considered in this study and potentially derived from CBD thermal degradation have concentrations below the instrumental LOD.