Genesis (2) - September 13, 1956 - S1-E2
Continuity mistake: When Sam ejects from the X-2 and parachutes to safety, he lands on the desert floor and the chute comes down on top of him, covering him completely. In the very next shot, we see him lying face up and the parachute has entirely disappeared.
Play It Again, Seymour - April 14, 1953 - S1-E9
Revealing mistake: After Sam nearly falls down the elevator shaft, the scene fades and comes back in with Sam speaking to the landlord about the incident. The landlord brushes off Sam's hat with his hand and hands it to him. The brushing motion was played in reverse first to extend the length of the action.
Piano Man - November 10, 1985 - S3-E15
Revealing mistake: When Sam is driving the truck through the fog/smoke, Al tells Gooshie to center him on Lorraine but Al doesn't jump out. The shot cuts to a front view of the fog. The road noticeably jumps forward because there is a dissolve transition in this shot, even thought its the same angle. It's likely it was done to lengthen the shot.
8 1/2 Months - November 15, 1955 - S3-E12
Audio problem: Sam and Al are walking along the road when they come across the father of the baby. Sam tells Al that he's just a boy. Al replies that Sam is just a girl. Al's mouth appears to be saying "guy" or something else and the line is dubbed.
8 1/2 Months - November 15, 1955 - S3-E12
Continuity mistake: When Al is talking to Sam in the beginning about having to deliver the baby before he leaps, Sam gives Al a funny look. The scene cuts and instantly Al has a cigar in his mouth. We never see him put it in his mouth.
A Little Miracle - December 24, 1962 - S3-E10
Revealing mistake: The fractal of the star stops at a point just below the top of the frame, when in reality it should keep going. This gives away that the star is superimposed over the shot. Oddly enough, when it starts snowing, the effect looks normal.
A Little Miracle - December 24, 1962 - S3-E10
Revealing mistake: The video image over the building that Al shows Michael Blake is placed incorrectly. The edge of the effect is blatantly visible. This effect is corrected later when Blake asks to see the plaza again and the name is changed.
Maybe Baby - March 11, 1963 - S2-E20
Factual error: "Dancing in the Streets" by Martha and the Vandellas plays while the characters are driving. The problem is, the episode is set in 1963. That song was released in 1965.
A Portrait for Troian - February 7, 1971 - S2-E11
Factual error: When the second earthquake happens, certainly we would see evidence of the water shaking but the water is calm. In a real earthquake, the water would be sloshing around.
Disco Inferno - April 1, 1976 - S2-E2
Audio problem: When Chris is performing, and we see his dad watching, one of the scenes has poor audio sync. The music is ahead of his singing.
Disco Inferno - April 1, 1976 - S2-E2
Continuity mistake: Sam is buttoning up his shirt while at the bar. His hands are about halfway down his shirt. Cut and we see him from another angle. His hands are now down.
Play It Again, Seymour - April 14, 1953 - S1-E9
Revealing mistake: Sam opens his left hand when talking to Al at the beginning. His reflection does not. His reflection just points his finger.
The Right Hand of God - October 24, 1974 - S1-E4
Continuity mistake: Near the beginning, Sam has a cut on his left eye from the fight which they apply a bandage to later. The cut briefly disappears when Sam is talking to the sister, only to reappear.
Genesis (1) - September 13, 1956 - S1-E1
Continuity mistake: Al is talking to Sam near the hanger about his options regarding the pilot. When we see Sam and the back of Al's head, there is a significant shadow on Al. It isn't there in the opposite angle. On top of that, since Al is a hologram, shadows shouldn't affect him.
Catch A Falling Star - May 21, 1979 - S2-E10
Continuity mistake: The makeup lady puts a moustache on Sam right after he leaps into the man. A stagehand bursts in, telling him it is time to go on. The moustache is now gone, and the makeup lady puts it back on Sam's face.
Piano Man - November 10, 1985 - S3-E15
Continuity mistake: The old Ford pickup Sam steals to chase them is noticeably different than the one we see being driven later, including the front end, side, and roof damage, different side mirror type, no antenna on driven truck, and a different license plate number. (00:35:50)
Leap of Faith - August 19, 1963 - S3-E3
Revealing mistake: The newspaper Father John holds up has the headline "Youth Hit By Train", but the article text under it talks about Diane Feinstein's election race against John Van de Kamp for California governor in 1990, the year the episode was filmed. Other article texts do not match either. The text under the Bangladesh Flood article talks about Germany's reunification, which also happened in 1990, after the Soviet collapse. The paper is a copy of the Los Angeles Times with the titles and date changed. (00:05:10)
Maybe Baby - March 11, 1963 - S2-E20
Factual error: At the beginning when escaping, the song playing on the radio in the truck is "My Boyfriend's Back" by The Angels, which was released in July 1963, four months after the episode's date of March 1963. (00:04:00)
Leaping in Without a Net - November 18, 1958 - S2-E19
Visible crew/equipment: When driving to Denver we see the trucks with trailers go around a curve, and two modern cars are briefly visible on the right along with the knee of a crew member. The cars are probably the parked cars of the camera crew. (00:36:25)
Her Charm - September 26, 1973 - S2-E15
Factual error: When they arrive at the Federal Building, an exterior shot shows a green Karmann Ghia exiting with California license plate 1MMW713, except 1XXX plates first were issued in 1980. A blue California plate for the time should have been just XXX. (00:06:20)
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.