If its some rando at the park spraying liquids of unknown origin on strangers, maybe calling the cops is reasonable. Calling the cops on a neighbour at a party for spraying you accidentally while following a child, overreaction. I hope they have any more parties and specifically ban that jerk neighbour’s who called the cops.
Pretty sure its a natural gas powered water heater, so that would be the gas supply line. As to the incandesance, no clue.