The Wrong Stuff - January 24, 1961 - S4-E7
Factual error: Al says he was an astronaut and flew around the moon, describing a mission that sounds precisely like Apollo 8 (10 orbits around the moon, reading of Genesis, etc). In the season 2 finale episode 'MIA, ' set in 1969, Al says he was shot down in Vietnam two years earlier, in 1967, taken prisoner and not freed until 1973. The Apollo 8 mission flew in Dec. 1968, meaning Al would have been a POW at the time. Also, NASA astronauts aren't generally sent to serve as pilots in active war zones.
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.