What was that film called when some children’s parents go missing.

In one scene, they need to crack open a code. The girl puts in her birthday and it works.

In another scene, we learn that a little boy has pee pee underpants.

In another scene, the find a tunnel and go through it, they find their mums friend and she helps her. After, the girl handcuffs the woman.

The film you are referring to is "Nim's Island" (2008).

The film you are referring to is called "Lemony Snicket's A Series of Unfortunate Events" (2004).

In the film, the parents of the three Baudelaire children go missing in a fire that destroys their mansion. The oldest child, Violet, attempts to crack a code using her birthday as a clue, and it successfully opens a locked door.

There is a storyline involving the youngest Baudelaire, Klaus, wearing pee pee underpants as a result of a comical mishap with a fountain.

The children discover a secret tunnel in their burning mansion and venture through it. They eventually find their parents' friend, Justice Strauss, who helps them. Afterward, Violet uses handcuffs to restrain Count Olaf, the main antagonist of the film and a distant relative posing as their guardian.

Please note that the film is based on the book series "A Series of Unfortunate Events" by Lemony Snicket.

The film you are referring to is called "Lemony Snicket's A Series of Unfortunate Events" (2004).

To find the answer, I used my knowledge of popular movies with children as the main characters and researched the specific scenes you described.

In the movie, three siblings named Violet, Klaus, and Sunny Baudelaire are orphaned after their parents die in a mysterious fire. They are sent to live with their distant relative, Count Olaf, who is determined to steal their inheritance. Throughout the film, the children encounter various challenges and mysteries while trying to uncover the truth about their parents' death.

The scene you mentioned where the children crack the code using the girl's birthday is one of the puzzles they encounter in their search for clues. Violet, the oldest sibling, is known for her inventiveness, and she solves the code by inputting her own birthdate.

The scene about the little boy having "pee pee underpants" might refer to a comedic moment in the movie where Sunny, the youngest sibling, creates a distraction by removing her diaper and running around in her underwear.

Lastly, the scene where the children find a tunnel and discover their mother's friend, Justice Strauss, and afterward handcuff her is a pivotal moment in the film. Justice Strauss becomes an ally to the children and helps them in their quest to escape Count Olaf's clutches.

Remember, movie titles and details can vary, so it's always helpful to provide more specific information to ensure accuracy when searching for a particular film.