What are some potential pitfalls when using PHP datetime functions on different server environments?

When using PHP datetime functions on different server environments, one potential pitfall is differences in timezone settings. To ensure consistent behavior across servers, it's best to explicitly set the timezone in your PHP code using the `date_default_timezone_set()` function. This will prevent unexpected results due to server configurations.

// Set the timezone to UTC to ensure consistent behavior
date_default_timezone_set('UTC');