Intertexuality is the way in which one media text references another or the concept of borrowing from, modifying, and recycling other media texts to create a new media text. It is often used to generate feelings of recognition, nostalgia, or familiarity for an audience experiencing a new media product.
The three types of intertexuality
Obligatory : An understanding that requires knowledge of a prior text
In this scene in Shrek 3, the audience would need to know the Disney princesses to understand the characters that are portraying them and the many references that happen.
2. Optional : A relationship to prior texts exists, but is not essential
In this scene in Kill Bill, the main character wears an outfit that is based off of an outfit worn by Bruce Lee. The outfit is not essential to the plot, but it is a direct reference.
3. Accidental intertexuality : No intention of intertexual relationship
I believe that the movie cover picture was coincidental, because when looking up the movie, there is no reference to the Beatles. Also in the sequel they use the same method of people walking the plank, but there are more people.