I have a small chilli plant. It's in a pot and yesterday I put it outside in the sun. When I brought it back inside some of its leaves had turned upside down. What is the problem?
The most likely explanation is too much sun too quickly - the chlorophyll content in the leaves is greatest on the upper surface, and its the chlorophyll that absorbs sunlight. Your plant, being exposed to sun suddenly, flipped its leaves to absorb less of it - this is not an unusual event on pepper plants and it shouldn't affect its fruiting. Next time you want to put it outside, introduce it to sun gradually by standing in a dappled shade spot for a day or three, gradually moving it into full sun as it grows.