11. Despite being aired for more than 5 years, it has only been a little over one and a half year since the outbreak.
The timeline of the show is a very slow one as the infection spreads rapidly and the human characters have to deal with the consequences and fight for survival on an everyday basis. In the season 1 episode “Wildfire”, Dr. Edwin Jenner says that it has been 194 days since the virus initially arose and only 63 days since it became a global contagion relative to the time of events of that episode. There is also a time skip of 8 months between the seasons 2 and 3, another time skip of 6 months between the seasons 3 and 4, and none between the season 4 and 5.(source)
12. One of the three severed heads see in season 6 episode “Who Will Save Your Soul” was made from a mold of Johnny Depp’s head.
In the scene where Andy, Jesus and Nick are trying to decide which of the three severed heads they should take to pass off as Gregory’s in order to gain access to the Savior’s compound, the head on the right was actually made from the mold of Johnny Depp’s head. The head is an emaciated and old version of Johnny Depp’s face with a gaping expression, bearded and half balded head.(source)
13. The name of the doctor at CDC, Edwin Jenner, was a reference to Edward Jenner who developed the first vaccine for smallpox.
14. The car Dodge Challenger, which Glen steals in season 1, is the same car that Walter White bought his son in Breaking Bad.
The Walking Dead has Easter eggs scattered here and there giving the viewers pleasant surprises, recalling other TV shows from AMC, especially Breaking Bad. If Blue Sky Easter egg was one, then Dodge Challenger was another such nostalgic reminiscence. The name of the general manager of the dealership to whom Walt returns his shiny red car so as not to draw attention to their family business in season 4 of Breaking Bad was Glen. In season 1 of The Walking Dead, Glen is seen driving the same car.(source)