Author's Riddles

Question: Why can't people walk into mirrors?

Water Bottles (medium)

Question: Two men/women in absolutely identical conditions have two of the exact same water bottles (full of water). An hour passes, and the temperatures of the water inside the bottles are measured. The temperature of one of the bottles is noticeably higher than the temperature of the other. Assuming that the temperature of the setting they were in, as they were both the same, had to do with the change in temperature of the water, why are they different?

Venom (medium)

Question: A man obtains a vial of the deadliest venom on earth. A single drop could kill a fully-grown man within seconds. He drinks the entire vial and after a minute, he is not harmed. How did he do it?