Continuity mistake: When Howard is almost done moving out of his mother's house, there is a table in front of him with a measuring device in the top corner. In one shot, the device moves to the opposite corner of the table. In a few shots later, the item returns to its original position.
Continuity mistake: Sheldon is returning Amy's scarf and says, "You wore it the night we went ice skating, remember?" to which Amy replies, "You mean the night that I went ice skating and you stood at the rail Googling the symptoms of hypothermia." But in episode 8-12: The Space Probe Disintegration, Amy states that she cannot go ice skating because she has "unnaturally brittle ankles." (00:04:55)
Continuity mistake: When Howard is on the mound, the shot from behind the plate shows a player ready to catch the ball in a uniform shirt. The next long shot from the stands shows a catcher in full gear, and then back to behind the plate to the player in uniform shirt only.
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.
Continuity mistake: The Stevenson Award in Sheldon's office reads "Sheldon Cooper, PhD." But, in the "Dennis Kim" episode we are told Sheldon was 14.5 years old when he earned that award - 1.5 years before earning his PhD at age 16, so the award should not show the title of PhD.
Continuity mistake: After the 'Ramona' conversation between Sheldon and Penny ends, Sheldon leaves Penny alone on the couch. Penny looks up to the "Amy and Penny" painting and says "Don't look at me like that, I tried." In S10 E10, Amy gave the painting back to Penny, which was hung in Leonard's living room.
Continuity mistake: In the laundry room when Penny is talking to Sheldon, Sheldon takes some time arranging a blue shirt on his plastic laundry folder. Then it suddenly turns into a pair of socks, which he folds and then picks up the blue shirt again. There was not enough time for him to switch out the shirt for the socks. (00:06:30)
Continuity mistake: Howard, Leonard and Raj play Jenga in a strange sort of way. Most notable is the playing order, 1. Howard, 2. Raj, 3. Raj, 4. Leonard, 5. Howard. When it's Leonard's turn he doesn't move any bricks, only pokes the tower and it's then Howard's turn. When its Raj's first turn he puts a brick on the top of the tower. When it's his turn again, the brick is gone and he puts a new one in its place.
Continuity mistake: When the girls take Sheldon out dancing, he mentions that he considers himself a proficient dancer due to his Cotillion training when he was a boy. But in S1E7 The Dumpling Paradox, when Leonard suggests that they could have gone dancing with the girls, Sheldon said that nobody in the group - including him - could dance.