Do you mean tank as in a propane tank or exploding barrel? Because I think it's something hanging from a ceiling actually, maybe a light fixture or something. It looks to me like he's shooting at whatever is suspending it in order to make it fall on the guy. So the LOL-tastic explosion isn't an explosion since it's just a big device filled with electronics as opposed to anything explosive. Could be wrong since it's hard to see, but that's the way I took it.