A short cause case is a civil case in which the time estimated for trial is 5 hours or less. Please see the rule of court that I have copied for you below. A short cause trial is your entire trial, and you need to prepare everything you would intend to prepare for a regular trial (also known as a long cause trial). For a short cause trial, you need to put together all of the documents and other things you intend to use as exhibits, as well as get your witnesses ready to testify. The court will likely expect a trial brief from each party. If there is any evidence you want to have excluded or other preliminary matters you want the court to address, you need to prepare motions in limine. These are usually delivered in advance to the court and to your opposing counsel. You will also want to prepare a brief opening statement and examination outlines for direct and cross-examination of witnesses. The court may also require advance submission of lists of witnesses and exhibits, as well as pre-marking of exhibits. There may also be a preliminary conference required by the court in advance of your court hearing. Check the local court rules to understand the timing regarding the submission of any of these documents in advance of the trial. Local court rules are available on most court's websites. It would not hurt to give the department you are assigned for trial to a call to find out about any of the court's preferences in terms of handling of exhibits, approaching witnesses, and the like.
A trial is a lot of work to prepare for, and experience counts. I suggest you get an attorney involved immediately to help you.
2008 California Rules of Court
Rule 3.735. Management of short cause cases
(a) Short cause case defined
A short cause case is a civil case in which the time estimated for trial by all parties or the court is five hours or less. All other civil cases are long cause cases.
(Subd (a) amended effective January 1, 2007.)
(b) Exemption for short cause case and setting of case for trial
The court may order, upon the stipulation of all parties or the court's own motion, that a case is a short cause case exempted from the requirements of case management review and set the case for trial.
If a short cause case is not completely tried within five hours, the judge may declare a mistrial or, in the judge's discretion, may complete the trial. In the event of a mistrial, the case will be treated as a long cause case and must promptly be set either for a new trial or for a case management conference.