There is a Bernadette doll in the bookcase behind her in the apartment wearing the same outfit she is wearing in the scene.
Leonard brings Sheldon a sailor hat, fulfilling a promise mentioned by Sheldon in the previous episode, The Hofstadter Insufficiency (2013).
Raj refers to two different versions of the movie "Freaky Friday" as the "original and Lindsey Lohan". Apparently, he is unaware that three versions of the movie existed at the time: the original, starring Jodie Foster (Freaky Friday (1976)); the first remake, starring Shelley Long (Freaky Friday (1995)); and the second remake, starring Lindsay Lohan and Jamie Lee Curtis (Freaky Friday (2003)).
In this episode, Sheldon says to Stuart, "Oh, you make me laugh, sad clown." Sad Clown Productions is the name of Mayim Bialik's (Amy Farrah Fowler) production company.
Title Reference: The title refers to Sheldon finding out that Leonard has been deceiving him by hiding out at Penny's and not tell him that he was home.