During the Credits
There are no extras during the credits of Clerks.
After the Credits
Jay can be heard saying, “Noinch, noinch, noinch, shmokin’ weed, shmokin’ weed, doin’ coke, drinkin’ beers…”.
There is also an extra scene after the alternate ending credits that shows Kevin Smith (with his beard shaved off) stealing cigarettes from the store.
Alternate Ending (spoilers)
There is an alternate ending on the DVD version that shows Dante being shot at the store.