Impractical superweapon ideas and engineering limits

Which real-world superweapon concepts does the panel find most absurd, excluding flying aircraft carriers?

The choices include tunnelling through the Earth and Germany's V-3 gun, followed by examples of trying to control unsuitable explosive energy sources.

Deep tunnelling as a shortcut for military movement is criticised for ignoring excavation difficulty and heat. Germany's multi-charge V-3 gun is another participant's choice. Dynamite guns and a vaguely remembered explosive-powered vehicle idea extend the discussion to controllability. The vehicle recollection is uncertain and no precise design is identified. The examples focus on the gap between energy on paper and practical engineering.