Mirror Image - August 8, 1953 - S5-E22
Visible crew/equipment: After Sam tells Al the bartender that he wants to talk philosophy, Al tells Sam that he's not just the bartender, he's also the owner, then when Al walks behind the counter the actor's T-mark can be seen on the floor. (00:26:50)
Memphis Melody - July 3, 1954 - S5-E21
Visible crew/equipment: While Sam and Sue Anne are singing Amazing Grace at the diner, right after the shot of the cook starting to play the harmonica, in the next wideshot the actor's T-mark becomes visible on the floor at the bottom, left side of the screen.
Answer: Sam threw items off the raft to lighten the load, so it wouldn't sink, in doing so he made the raft less heavy. Which made easier to float with the currents, if it was heavy the raft would have moved slower and not moved so far.
Except that Al said that immediately after throwing stuff out of the boat four hours passed and it was shown that they didn't really move from where they were. They were still in the same spot. Forgot to ask this too. When Sam and Vanessa are stranded on the island, one of them, can't remember who, did something and when Al appears, he tells them that because of it, time had suddenly skipped several more hours and if the event hadn't been interrupted, they would have been rescued by a boat. So, what happened on the island that once again caused time to speed up? It seems kind of strange that time could move so quickly on the island, especially since it was still day time and it never showed any sort of changes like the sun or clouds moving.