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)
Her Charm - September 26, 1973 - S2-E15
Revealing mistake: When Al is helping Sam find Dana in the forest, his feet keep kicking up or moving the dirt and leaves, which a hologram shouldn't be doing. (00:39:00)
Her Charm - September 26, 1973 - S2-E15
Factual error: Sam is wearing a Casio calculator watch, which we are shown up close when he is driving the laundry van. The first calculator watch was made by Pulsar in 1975, and Casio's first calculator watch was released in the 1980s, long after this episode's 1973 date. (00:15:25)
Another Mother - September 30, 1981 - S2-E13
Factual error: When the boys are talking to Jackie to get her to cooperate with their plan, the song Shake It Up by The Cars is playing, except the show is set at September 30, 1981, and the song was released in November 1981. And it wasn't a pre-release demo version on the radio since the song was still being mixed at Syncro Sound Studios in early October. (00:23:00)
Animal Frat - October 19, 1967 - S2-E12
Factual error: When Sam is in the library, there are multiple book titles visible that were published after the show's date of 1967. The clearest is when Sam and Duck tussle, the book "Men How To Understand Your Symptoms" falls on Sam - this book was first published in 1986. (00:29:00)
Jimmy - October 14, 1964 - S2-E8
Factual error: The episode is set in 1964. When Frank and Jimmy first arrive at the dock and some of the dock workers are harassing Jimmy, there is a nice set of period appropriate cars in the foreground that the other dock workers are around, but in the background we see street traffic with 1980s cars driving by. (00:10:50)
Her Charm - September 26, 1973 - S2-E15
Revealing mistake: When driving to the cabin, the mileage markers on the roadside indicate they are in Los Angeles, nowhere near Boston or Baltimore. (00:20:30)
Thou Shalt Not... - February 2, 1974 - S2-E7
Visible crew/equipment: When Sam and Shirley go out of the bake sale to talk and she admits to having an affair and begins to cry, Sam reaches into his coat for a handkerchief, and a mic briefly drops down and is visible in the upper left of the screen. (00:29:00)
What Price Gloria? - October 16, 1961 - S2-E4
Continuity mistake: When Sam goes out of the window to save Gloria, part of the ledge breaks off, but in the near shots it is broken off almost to the corner near Gloria, while in the shots from below most of the ledge is still intact. (00:35:45)
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.
Genesis (2) - September 13, 1956 - S1-E2
Deliberate mistake: When Sam ejects and lands on the ground, the closeup is a flipped shot, note the "US Air Force" is backwards on Sam's helmet. (00:19:10)
A Portrait for Troian - February 7, 1971 - S2-E11
Audio problem: Near the beginning in the tomb, a woman says "he's been dead for three years." Her mouth doesn't match what she is saying.
Catch A Falling Star - May 21, 1979 - S2-E10
Continuity mistake: When Sam is going on stage near the beginning, another guy peels off his moustache and says "imposter." The problem is, the makeup lady already removed his moustache earlier in the episode.
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.