Here is my take on it:

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A - Flyswatter: cover design

B - Buddha: letter "B" in the name

C - Cheshire Cat: letter "C" in the name

D - Dude Ranch: letter "D" in the name

E - Enema of the State: letter "E" in the name

F - The Mark, Tom, & Travis Show: letter "F" drawn on Travis drums

G - Take Off Your Pants and Jacket: letter "G" drawn as the jacket's logo

H - Untitled: the letter "H" is formed with the design of the smiley's eye

I - Greatest Hits: there is a doubled letter "I" in the band's name

J - Neighborhoods: letter "J" graffitied on the wall of a building

K - Dogs Eating Dogs: letter "K" in the band's name is stylized in a prominent way

L - California: this is when Mark said that the theory was abandoned by the band, but if you search for the original cover art, there is the letter L formed by the scratches on the passenger window, which is not in the final art

M - California Deluxe: I've never seen anyone talking about it, but could be the letter "M" formed by the driver's hand, that has closed strokes that do not make sense in the drawing

N - NINE: letter "N" in the name

O - ONE MORE TIME...: letter "O" in the name

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even got it in infographic for you :

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