Admissions officers don't have time to investigate all of these smaller claims, but they will almost certainly do some research if you participated in a very prestigious program or won an impressive award. The greater impact the claim has on your potential as an applicant, the more likely it is that schools will do some fact-checking. It's never worth it to lie on your college application! It will derail your education down the line if discovered (you'll get kicked out or have your degree revoked).