Maybe your manager is required to review this case with you as some sort of formal process because the patient came in through the ED and died in the ICU. Just go in with a good attitude and be open to learning how you can do better next time (not saying you didn't do a good job in this instance; I do not know what you did/didn't do, but I'm giving you the benefit of the doubt that you did your best).
Any time a person presents with head pain and an abrasion to their forehead, it buys them a non-contrast head CT, drunk or not. A long term alcoholic would certainly be at risk for an intracranial bleed due to reduced clotting factors r/t alcoholic liver disease. That he has an unsteady gait, nausea, and decreased LOC could be related to either alcohol or head injury or both, and you have to rule out the worst case scenario.
Why it took hours for him to get his head scanned, I do not know. Was it that long before he was seen by an MD? Was the scanner backed up because of high patient volume?
Basically, based upon the details you presented here, he should have been seen and evaluated sooner rather than later. Part of that involves the triage process. If he walked in through the lobby, then the triage nurse would have assigned an acuity. If he came in by ambulance, then the receiving nurse (you?) would have done so. Was he assigned an appropriate acuity for his condition?
If he was triaged as a 3, for instance, and died in ICU, I would imagine this would automatically trigger a review.
If anything, your responsibility in this instance would have been to get him evaluated sooner rather than later, and if the MDs are behind and it's taking them too long to see the 2s (what I think he probably should have been, according to your post), then you should have found an MD to ask for what you need, such as an MBA and a non-contrast head CT. At least get the ball rolling until a doc could see him. Get some fluids going, do a neuro check, etc.
It sounds like he was just thrown into a bed and forgotten about because he wasn't seen as very high acuity, and you guys were busy. That may or may not be the case, but that's what it sounds like....and if it sounds like that to me, it could sound like that to a jury.
Now, I could be completely off base and making a lot of assumptions here, because you haven't posted that much detail, which is good. It's really best to try and stay anonymous here with questions of this nature.
Whatever happens, good luck.