Sergeant Shishka mentions he notices neither Steve or Eddie are on his list of new recruits (since they only snuck onto base to get Waldo back). If this were the case, he should have also noticed Waldo wasn't one either. As Waldo simply stood at the end of a long line, rather than signing enlistment papers.
Sergeant Shiska doesn't put his legs together after throwing the grenade and hitting the floor.