Not an eyewitness to either of these, but can confirm them:
The summer I was at OCS ('04) one of the 6-week candidates (I'm assuming one of the juniors) tried to go UA at the start of 1st increment by swimming away from OCS. I'm not sure whether he thought he was going to swim to Maryland or just get outside the limits of the base on the Virginia side, but he wound up landing a few hundred hards away from where he started, getting hauled in front of the Colonel and leaving OCS a short time later anyway after out-processing. This one has almost taken on the status of an urban legend, although I know it's accurate since the Col. told the same story both at PLC-combined pick-up and at family day.
Same summer, while 2nd increment was in-processing, 3 guys on watch from my company (COG taking 2 sentries either to or from the parking lot) see a cab pull onto the parade deck right in front of the barracks. Two candidates in civvies sprint out and get in, then the cab hauls ass out of there.