Lucille Bluth's prison ID number is "07734," which is "Hello" backwards and upside down. This is a call back to Annyong, which is "Hello" in Korean.
There are several clues hidden through the show that allude to the fact that Tobias Fünke is actually a very light-skinned African American. The Narrator says that Lindsay flirts with Herbert Love because he reminds her of Tobias, which could be because they are both African American.
When Lindsay (Portia de Rossi) and Marky Bark (Chris Diamantopoulos) are in the Penthouse, a Facebook notification can be heard in the background. This is because Mitchell Hurwitz know that most people are watching Season Four on their computer.
Lindsay and the crowd at Cinco de Cuatro chant the words "Put up this wall! Put up this wall!" the same way the Bluth employees chanted "Don't buy! Don't buy!" in The Cabin Show (2005), and "Speech!" in Marta Complex (2004).
Lindsay (Portia de Rossi) ran for class president in 1982. Gob (Will Arnett) and Michael (Jason Bateman) ran against each other for student body president in high school, as mentioned in episode 2.14, The Immaculate Election (2005).