I'm not sure why there is a misunderstanding (in the trial) about Dr. Horn's autopsy findings.
Dr. Horn signed Travis Alexander's autopsy on July 15, 2008 - On the 7-15-08 autopsy Dr. Horn states "Cause of Death as Sharp Force Trauma of neck and torso. Manner: Homicide."
Dr. Horn's Report of Autopsy of Travis Alexander Date of Examination is June 12, 2008. Again, it is signed by Dr. Horn on July 15, 2008. Dr. Horn writes the date 07/15/08 in his own handwriting along with his signature.
I do not know if Dr. Horn meant to write 06/15/08 and by accident wrote 07/15/08 (considering the date of examination was June 12, 2008). After examining Travis Alexander - Dr. Horn would have to wait on toxicologically results.
According to The Report of Autopsy there is about a month between the time that Dr. Horn examined Travis Alexander's body - wrote and signed his report. However, on his report Dr. Horn list the "cause of death as Sharp Force Trauma of neck and torso."
Perhaps Det. Flores was going "back and forth" between which injury came first. Therefore, Det. Flores has a memory of discussing this with Dr. Horn - and perhaps was not certain himself until his report was finalized on July 15, 2008.
I do not know. However, I once thought that Arias shot Travis Alexander first. However, after reading the autopsy and seeing some of the Medical Examiner's photos - I believe that Arias stabbed Travis Alexander first, and, that Arias shot Travis Alexander last.
Here is a link to Dr. Horn's Report of Autopsy for Travis Alexander. I hope that it is helpful. It is confusing as to why there was any misunderstanding in court about how Travis Alexander was murdered - given Dr. Horn's report.
http://cnninsession.files.wordpress.com/2012/10/redactedtravisautopsy.pdf