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A Sneeze, Detention, and Sissy Spacek - S1-E13
Visible crew/equipment: When Sheldon is running away from Mary in the garage, the set lights are reflected in his helmet. (00:18:00)
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A Stunted Childhood and a Can of Fancy Mixed Nuts - S2-E10
Visible crew/equipment: When Missy puts her sunglasses on in the car, a square stage light is reflected. (00:04:00)
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Visible crew/equipment: When Missy runs through the house at the start the stage lights are reflected in her sunglasses. (00:02:25)
Answer: It is shown numerous time in The Big Bang Theory and Young Sheldon that Georgir Jr is not the smartest kid going. They simply tell him Sheldon is getting a hair cut as it is believable. It's also shown that Sheldon has had the same style hair cut since he was 5. Since he is 9 in Young Sheldon, he's had the same style for over 4 years already. Easy to overlook that he hadn't actually had it cut after that long.
Ssiscool ★