Here's my list
1. The huge beast from the first season that was never actually seen
2. Polar bears on the island
3. The miraculous healings many of the characters experienced
4. The black mist/smoke that the african guy encountered
5. The original guy who was in the hatch
6. Walt
7. Michael
8. The meaning behind the numbers
I know I'm missing more things that were never explained, but that's all I can think of for now.
Your theories are welcome
1. The huge beast from the first season that was never actually seen
2. Polar bears on the island
3. The miraculous healings many of the characters experienced
4. The black mist/smoke that the african guy encountered
5. The original guy who was in the hatch
6. Walt
7. Michael
8. The meaning behind the numbers
I know I'm missing more things that were never explained, but that's all I can think of for now.
Your theories are welcome