The Big Bang Theory: 15 Insane Details You Definitely Missed
13. The Apartment Building Has A Locked Door
Throughout the series, it's extremely common to see anyone - from Howard, Raj, and the rest of the gang to various delivery drivers - freely enter Sheldon, Leonard, and Penny's apartment building. This is in spite of the building featuring a locked front door to the lobby!
As shown in season eleven's "The Gates Excitation", the front door requires a key to open. In this episode, Sheldon went inside and instead of holding the door for Leonard to follow, he didn't, causing it to shut and Leonard to have to use his key.
Though it's plausible that those living in the complex have the ability to buzz in visitors, as is trivial with such buildings, it's strange that this is never acknowledged and visitors just show up on the regular.
This isn't the only niggling issue with the apartment building either...