Default Camera didn't save .. is there a temporary directory?

So yesterday was taking a lot of photos on a day out, using the Google Camera app .. funny thing was happening though; often would switch to the camera but the Capture button was 'grayed out' and had to quit it and re-enter to get it to work. Afterwards realised a lot of the photos I took were not there .. Figured that what was happening was, I would take the photo, press home button or power off and it evidently had not finished saving, or as HDR was on, doing the processing. Never seen this before but maybe just a freak one off or to do with the updated Camera app released recently. But my question is; is there any temporary directory files might have been saved to before doing the HDR stuff nad saving to gallery, or I guess maybe that is all done in memory and I am out of luck?