Corrected entry: Several times throughout the show, Leonard makes reference to having sleep apnoea, a condition where the airways close up when you are asleep and you stop breathing for periods of time before your body's reflexes kick in and wake you up. However we also see him sleeping numerous times but he doesn't have any form of cpap (Continuous Positive Airway Pressure) machine. This is vital for anyone who has sleep apnoea as it pumps air into the users airways via a nasal cannula or face mask to keep the airways open and stop the user from stopping breathing. Since sleep apnoea in the most extreme cases can cause death (depending on type of sleep apnoea) a cpap machine is vital and should be seen whenever we see Leonard sleeping or in bed.
Corrected entry: Throughout the series Penny complains that she is broke, and is paid minimum wage at The Cheesecake Factory. She even takes on additional duties as a barmaid to try to earn extra money. We also learn that Sheldon and Leonard live together as their apartment is too expensive for one person - Sheldon says he would be happy to live alone if he 'could afford the rent'. Penny's apartment is almost identical to theirs - it can't be that much cheaper. So, if two University lecturers can't afford an apartment in that building, how on earth can a waitress on minimum wage do so?
Corrected entry: Leonard and Sheldon live in 4A and Penny in 4B. Yet when they go to the mailbox downstairs, Sheldon's mailbox is the upper left one while Penny's is the third or fourth one from the left. Mail boxes have to be in apartment order, not necessarily for the tenant who could remember where their box is but for the mailman to be able to use the apartment number as to placement of the mailbox. Whenever a sub carrier would do the route, he wouldn't be able to follow the random pattern.