The Luminous Fish Effect - S1-E4
Continuity mistake: When Penny comes into the apartment to ask if Sheldon needs anything from the market, between the few shots, the position of the napkin and the pile of eggs on the plate he is holding changes. (00:05:15)
The Luminous Fish Effect - S1-E4
Continuity mistake: When Sheldon asks his mum why she's there, his mums hand on his chest changes position. Note the distance to his elbow. (00:11:40)
The Luminous Fish Effect - S1-E4
Continuity mistake: When Penny is asking if Sheldon has ever done anything like this before she is holding her plate with 2 hands in one shot and 1 hand in the next. (00:13:20)
The Luminous Fish Effect - S1-E4
Continuity mistake: When Sheldon's mom is saying the prayer, the bread roll that Raj is holding swaps hands, and then it disappears in the shot where she tells them they don't have to join in with the end of the prayer.
The Hamburger Postulate - S1-E5
Visible crew/equipment: At the start when we see the guys sat at the table, a small white tape marker is visible on the floor where Penny will stand in a few minutes. (00:02:30)
The Hamburger Postulate - S1-E5
Continuity mistake: When Howard demonstrates being a human beat box to Penny, the way she holds her pen changes instantly. (00:02:50)
The Hamburger Postulate - S1-E5
Character mistake: Leslie states that heroin causes pupils to dilate, like when Leonard sees Penny. Opiates cause pupils to constrict. (00:06:20)
The Hamburger Postulate - S1-E5
Character mistake: When Sheldon knocks on Penny's door to seek advice about the tie on Leonard's doorknob, he does not use his typical triple knock. (00:07:43)
First time he knocks 3 times is in Episode 2 of Season 1. First time knocking 3 times followed by saying the name is episode 10 of Season 1. The ritual of 3 knocks and 3 times saying the name and then stopping is Episode 5 of season 2.
Sheldon knocks three times because he once walked into his parents bedroom and saw his father with another woman. He's been doing the triple knock since he was a teenager.
Yet, he didn't in the show till Season 2. Funny ain't it?
Suggested correction: A one-time lapse in someone's usual behavior does not count as a "character mistake", even in the case of someone given to ritualistic behavior as Sheldon is.
Ah, but in an episode he explains he had developed this particular ritual at age 13 after walking into his parent's bedroom without knocking and seeing his father having sex with another woman. He says he started knocking 3 times since then and would never forget. So its not consistent and a mistake as this is not the only example one can name.
The Hamburger Postulate - S1-E5
Revealing mistake: When Penny leaves when Leonard and Leslie are in his room, she opens the apartment door and the hallway is isn't present. It's just a chipboard wall. (00:09:50)
The Hamburger Postulate - S1-E5
Continuity mistake: When Sheldon is ranting about his board being changed, there is one shot where his hand is uncovered then covered by the blanket. (00:12:00)
The Hamburger Postulate - S1-E5
Continuity mistake: At the end when Sheldon has got a burger, the amount of burger left changes depending on the camera angle. Most noticeable when he asks Penny about permanently reserving the table - between shots the lettuce disappears, the bun changes colour, and the bite marks change.
The Hamburger Postulate - S1-E5
Audio problem: When Leonard and Leslie continue to practise together after the other two musicians have left (Leslie now being the only violinist), vibrato from a violin can be heard - from observing Leslie's left hand she is not applying it.
The Hamburger Postulate - S1-E5
Continuity mistake: Leonard and Leslie are rehearsing the violin and cello in the guys' living room, and when they leave the room to go to Leonard's room, Leonard's cello and stand are still in front of the comfy chair. When Sheldon gets home, the cello and stand are gone, and only Leslie's closed violin case is left on the sofa. And she picks it up and leaves with it. How did the violin get back in the case.
The Hamburger Postulate - S1-E5
Continuity mistake: When Sheldon is explaining to Leonard why a Cheesecake Factory Hamburger is superior to a Big Boy Hamburger the number of fries on Leonard's plate noticeably changes between shots.
The Middle Earth Paradigm - S1-E6
Continuity mistake: When Leonard is talking to Sheldon in the kitchen about the party, Sheldon is pouring juice. In one shot he places the bottle cap on the bottle yet in the next shot his hand is down on the counter with the lid in it. (00:04:50)
The Middle Earth Paradigm - S1-E6
Visible crew/equipment: When Sheldon is being asked not to embarrass Leonard, the stage lights can be seen in the pans behind him. (00:05:10)
Continuity mistake: When Leonard and Sheldon are talking with Penny during the scene where she is being allowed to sleep on their couch, the pullstring on her hooded jacket keeps alternating from hanging loose to being caught inside the top of the jacket. (00:07:40)
Character mistake: Wolowitz warns his fellow halo players that their enemy is "charging his Plasma Rifle". This is impossible since only the plasma gun can be charged up. (00:20:00)
Factual error: Sheldon has a rigid schedule. Halo Night is known to be on Wednesday night. Penny sleeps on the couch in Sheldon and Leonard's apartment. The following morning, Sheldon cannot watch Doctor Who on BBC America because Penny is sleeping on his spot on the couch. He states that he has been watching Doctor Who every Saturday at 6:15 a.m. The following morning should be Thursday.
Character mistake: Raj cannot talk with a woman around, but when Leonard claims they'd have to cut him in half to play teams, he blatantly argues back, and Penny is present with them. Regardless of if he was facing her or not, he shouldn't have said anything.