I known what you mean about not being able to find all of your stuff.
In the Diary of Lorenzo Mears of Union County is where he states that His company from El Dorado was assigned with two companies of infantry from Arkansas and a company from Maryland in the Spring of '62. Evidently these companies had not acted as a combined unit until then. They were ordered to Ransom's Brigade in Richmond and then to Yorktown. He states that it was when they were ordered to Richmond that they were told to only carry what their marching order of 35 pounds would allow. Mears stated that he had to leave several suits of clothes and underwear behind to be picked up later.
This seems to indicate that the leaving of the camp gear and flag was intentional. That it was Extra equipment and not left in haste, but possibly to fool the Yankee observers, across the Potomac, but they were not fooled and the empty camp was soon discovered and raided.
I would love to see the Union report on the incident. To compare with Mears Diary.