What are the potential pitfalls or common mistakes to be aware of when working with PHP date and time functions?

One common mistake when working with PHP date and time functions is not considering the timezone. It's important to always set the correct timezone to ensure accurate date and time calculations. You can set the timezone using the `date_default_timezone_set()` function.

// Set the timezone to your desired location
date_default_timezone_set('America/New_York');