When you're eating out and want to remember what you ate, use your phone to take a picture of your plate before you start eating. You'll remember what you ate more easily, and knowing you're going to take a picture might help you eat more mindfully.
It's easy to get off track when you eat out if only because it's hard to track what you're eating. Worse yet, you might decline a night out with friends just because you don't want to have to track the food you eat or you have a hard time remembering what you ate throughout the night. This helps.