Maybe this should be part of "The Things I Never Noticed Before" department.
Someone posted about this on Facebook the other day and I had to take a listen. Lalo Schifrin was tasked back in the 1960's with coming up for the opening theme song for the TV show "Mission Impossible". So the story goes that given the premise of the show, he thought it would be good spycraft to incorporate some Morse Code. So... if you listen to that opening beat ......dah dah, di dit ........ dah dah, di dit ....... dah dah, di dit.
You get "M" and "I" for "Mission Impossible". The timing is not perfect, but the discerning ear should be able to make it out. How many times I have heard that theme song and never noticed it before!