It should be noted that, in order to keep a flame, the hot air balloon would require some type of ignition (i.e. propane). So he could have been refering to the type of gas the TARDIS burns to generate hot air.75.8.232.255 17:32, July 2, 2010 (UTC)
- Yeah, I don't get it. I'm sure that the gas is what was used to produce the flame. What else would? The Thirteenth Doctor 18:03, July 2, 2010 (UTC)