Usually, throughout a trailer, whether it is shown at the beginning, edited throughout, or shown at the end of the trailer, the cast/credit/studio information will always be given. This is simply when the main members of the cast within the film are mentioned in the trailer, as well as information about the production companies involved and the company that has distributed the film. Other information that is also sometimes given is, the editors name for the film, the director of the film, and other members involved in the production, distribution or making of the film.
The Credits may be in the form of: Reviews - Some trailers have reviews from newspapers with a short opinion of the film, people are more likely to want to go and see a film if others already have and though that it was good. This creates a sense of wanting to know the storyline or you may miss out, as result creating more narrative enigma within the audience. Credits - At the end of every trailer there may be credits in small print, These are to some of the main people, for example producers, if the audience like a particular producer or editor this my draw their attention to the film. Quotes - Some trailers will have quotes from the film or original text, this shows convergence, audiences will be able to relate other texts to the film for example Fifty Shades of Grey which is based on a book. This is for the audience who may have already read this text to be recognised and cause them to want to watch the film. This will raise questions to the audience which fits with the narrative enigma.