If you have 24 hours to spend in Callander, there are several things you can do:
1. Visit the Callander Crags - A beautiful hike with stunning views of the Trossachs National Park. This will take around 2-3 hours depending on how long you spend enjoying the scenery.
2. Explore Bracklinn Falls - A picturesque waterfall and woodland walk. This will take around 1-2 hours.
3. Visit The Hamilton Toy Collection - A museum featuring an impressive collection of antique and vintage toys. This will take around 1-2 hours.
4. Enjoy a meal at Mhor 84 - A popular restaurant serving up delicious Scottish cuisine. This will take around 1-2 hours depending on how long you spend at the restaurant.
5. Visit Callander House - An historic building with beautiful gardens and exhibitions. This will take around 2 hours.
Overall, there are plenty of things to do in Callander to fill your 24 hours. Just be sure to prioritize what you want to see and do based on your interests and time constraints.