Most of the cloud forest's mammals and amphibians are nocturnal, and a guided night walk is the easiest way to see them. Several operators run them on private reserves around Santa Elena, typically a two-hour loop with torches and a naturalist guide who knows where to look.
Reliable sightings include kinkajous, tarantulas, two-toed sloths, eyelash vipers asleep on branches, and a variety of frogs and stick insects. Wear long sleeves and bring a small torch — the guide will have a better one but a backup helps. Book through your hotel, the visitor centre on the main square, or directly with operators like Kinkajou Night Walks or Refugio Hidden Valley.