While a computer checks that your documents are legitimate, a border guard carefully studies your ID photograph to compare it with your face. Colored contact lenses and a fake mustache would not raise much concern among experienced security staff. However, plastic or dental surgery could become a cause for detention and get you a few hours of additional inspection at the airport.
Before you go on a trip, you should carefully familiarize yourself with the customs regulations and baggage allowances. You want to be prepared so you don’t take anything that is prohibited into your destination country. Otherwise, your luggage may be confiscated, your entry may be denied, and you may even go to jail.