New Zealand
Teenage twin siblings, Rachel and Theo, on a summer vacation in Auckland visiting their aunt and uncle, meet a certain Mr. Jones, a mysterious man who helped find them when they got lost in the woods eight years earlier. Mr. Jones turns out to be an alien fighter from a distant planet who wants their help in fighting an alien giant slug family of eight members led by a certain Mr. Wilberforce who have arrived on Earth with plans for world domination. - IMDb
| Bajo la montaña |  Spain |
| A Hegy gyomrában |  Hungary |
| Moddermonsters (informal literal title) |  Netherlands |
| De Monsterplaneet (rerun title) | Netherlands |
| Tajemnica wygasłych wulkanów |  Poland |
| Under the Mountain |  USA |
| Under the Mountain |  South Africa |
| Under the Mountain |  Australia |
| Under the Mountain |  Canada |
| Under the Mountain |  West Germany |
| Under the Mountain |  United Kingdom |
| Under the Mountain |  Ireland |
| Under the Mountain |  India |
| Under the Mountain | New Zealand |
| Under the Mountain |  Singapore |
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Kirsty Wilkinson | Rachel |
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Lance Warren | Theo |
