Comparisons with the non finite values of infinity and NaN (not a number) lead to interesting failure modes. The in operator can mask some of these failures.

Asserts are a common way to quickly verify that inputs or other conditions are met. Python considers asserts as debug, leading to them sometimes being ignored.

Many methods exist within Python to create a tuple. Some are intuitive while others behave in strange ways. While type checking can help, complications abound.

Iterators as function inputs in Python can cause complex errors, due to storing references, differences between iterators and iterables, and other subtleties.

Using in for memberships in Python for iterables can behave differently. A list, dict, or iterator behave differently and type checkers may not find errors.