Ha, similar thing happened to me when I was a kid. We poured some gas on a flaming tennis ball and the flame went back to the container. It caused a huge wall of fire and got dark black soot all over the front of my friend's house. We spend hours scrubbing it and getting as clean as we could. I don't know if his parents ever noticed, we didn't get it 100% clean.
I lit a fuel filter on fire once and it had more gas soaked in it then I thought and pooof it went up and I kicked it and gas/diesel splashed back and lit my boot on fire and then about a 7 foot stretch of snow was on fire and the filter itself lmao