b997eee8_CCG___What_s_That_Inside_Joke___In_joke
[Card] Earth (1985) [Exp.] 7 Docs [Type] Ref [In-joke] 
The card is a Holiday not because the Doctor holidayed there, but because the cast and crew somewhat did in their off-hours shooting The 2 Doctors.
Unauthorized Dr. Who CCG - What's That Inside Joke?
In-joke