Airport fast train: don't queue at the ticket machines. On the left hand side, you can just swipe your credit card. If you need a copy of the ticket (expenses), request it afterwards at flytoget.no
Good luck finding Global Free tax refund desk because no one knows where it is. People outside security say it's inside and people inside security say it's outside. Still never found it.
If your flying international, you have to show your passports at the end of Te shopping area. Avoid doing this until you have to as there is not much on the other side! Otherwise fantastic airport.
Don't trust the pictures of food at the "foodmarket". Watch what people get for a while. Nudel wok was very dissapointing compared to picture (smaller too).
The new 19 gates bite it, big time! Sterile, ugly, not enough seating and if you're short on time, you're screwed. Come on OSL, you all can do better than this.