Yes, of course. You can change any property of any entry: the date/time, the location, the mood, the list of selected events, the notes and of course the image.
Just open any entry and tap on the pencil icon that is located on the very top right.
Now tap on the item that you would like to change (e.g. the smile to change the mood). If you want to edit the notes, just scroll down to the notes field and tap on it.
If you would like to delete an entry, scroll to the very bottom and tap on “Delete answer”.