Fortunately the flaming rubble of DOOOOOOOOOM should be relatively safe, unless it grows hands and tries to dismantle it (which in fact would be the trigger). AND! 'The acid of a gelatinous cube does not harm metal or stone (d20srd)'! Go go garrote!

I'll give that large disturbances in the structure of aforementioned rubble may cause the trap to go off prematurely, however. This is gonna get exciting.