Cyclopropane (Triangle alkane)

Cyclopropane is another markedly strained ring (the smallest simple ring geometrically possible, really):

It used to find some use as an anaesthetic. Strained rings being strained rings, however, it had a nasty habit of exploding. One movie made good use of this phenomenon (without commenting on it at all, there were just labels on the tanks!), where the villain used it as a weapon. No idea if the conditions were realistic, but at least the authors get some creativity points. Some have invoked the colorfully named banana bond theory to explain bonding in cyclopropanes.