The trick is to try for the highest "fidelity" as possible... go for realism as much as possible. If you have access to SimLab equipment, that's the ultimate! If not, are can make do with a CPR 'Annie'. Create a complete clinical scenario - admission history, 'chart' with clinical information, scripts for all the role play and good 'actors' to fill the roles.
* Visitor (role #1) comes running up to the nurses station "something's wrong in room 26!!! She made a funny noise and I don't think she's breathing!"
(code drill begins)
* "nurse" taking care of patient (role#2) provides assessment information to 'responders'
* "patient record" (mock up of chart or EHR in test/teaching mode" is available for reference
* Cardiac simulator used to provide 'rhythm
*Teaching (crash) cart with equipment, including mock drugs to administer, ET equipment, etc is available
*Physician responder (volunteer participant, but real doc) shows up & assumes role as s/he would in real life
Run the drill to a logical conclusion... but the most important part is the debriefing. Immediately after the drill, share observations, provide feedback and engage everyone in the analysis of what happened and how it could be done better. Ideally, you can capture it on video and show it to participants as part of the learning process.
Make it as realistic as possible - use case scenarios that would actually happen in that department. Invest some time setting the stage with your 'victim' to make it more realistic... fake blood, evidence of aspiration, dislodged central line, kinked foley ... Use 'real' Crash Cart stuff in order to give participants an opportunity to actually manipulate all the gizmos - you can beg outdated/expired stuff or order mock supplies that look like the real thing.
Investing time and energy ahead of time will pay off in participant reactions and engagement. Most educators are part 'performer', so you may even end up enjoying all the "drama".
BTW, it's best to set up signs around the area (after the event starts) to let passers-by and visitors know that it is a drill... otherwise, you may end up attracting unexpected participants who think it's the real thing.