I confess to a similar error. My elbow knocked the drain plug into the container, and I did not notice. Since it did not completely block the flow it did not initially look like a problem. So I took a break to let 'er drain.
Musta been a quart on the garage concrete.
I keep concrete cleaner and kitty litter just in case. After a half roll of paper towels it was under control. Then hit it with kitty litter (which you really need to grind in with your feet). Followed by the cleaner. It is cleaned but slightly stained now.