Corrected entry: At several points where town's folk are being chased in the mine, Chris mentions that the smallest spark will cause a devastating explosion. He then proceeds to take the motorcycle to rescue his aunt, and then starts the bike for a quick escape. As soon as the bike starts, they'd all be dead as a spark is needed to ignite the petrol, which would also ignite the methane gas.
Rooster of Doom
11th Aug 2004
Correction: Yes, but the spark to ignite the bike's petrol is contained inside the engine's cylinders (hence the phrase 'internal combustion engine'). For the engine to ignite the methane, some portion of its exterior would have to exceed the auto-ignition temperature of methane, which is over 1000 degrees Fahrenheit. Not likely.
Rooster of Doom