There is nothing common when it comes to sending anyone home on R/I-Day. If you have an injury that would preclude strenuous physical activity it is possible to be sent home. I've seen applicants show up at USNA on I-Day with casts and full leg braces (torn ACL).
If you are on a medication for something, Accutane for severe acne comes to mind.
There is no common list. If you have a new medical condition that wasn't disclosed to DoDMERB and the academy, depending on the severity you could get sent home.
The best thing to do is attempt not to get injured and stay healthy. Don't stress about being sent home on R/I-day.
