Check the Battle Gains Collection settings in the battle system you're using - when enabling Collect Immediately, you can enable dropping the different kind of loot (e.g. items, money, etc.) into the game world instead of adding it to the inventory.
If you want dropped things to still be there when leaving the scene and retunring, set the Save Drops setting (in Menus > Save Game Menu > Save Settings) to Game or Save (would also keep them in save games).