The Gorilla scene was scripted in the 4th draft of the Goonies script.
EXT. STREET - DAY
The Fratelli ORV squeals down the street, rapidly overtaking:
A large van. The elderly cab occupants (Simon and Simone Simian) exchange a contented glance. Simon now looks at his side view mirror, his expression instantly changing to panic as:
SIMONE: Simon, look out!
The van swerves hard right, allowing the Fratelli ORV to screech around it. Now suddenly looming up from behind the right side: A POLICE PATROL CAR!
Simon swings the large van back hard left to accomodate the patrol car as:
A second patrol car starts to overtake the van from the left side! The van spins in confusion, blocking the road sideways as a third patrol car skids to a stop in front of it, barely avoiding a crash.
The Officer inside jumps out, heads quickly for the van cab.
This road only runs two ways, pop, so......
He suddenly stops as he hears FRANTIC POUNDING and AGONIZED SCREAMS from within the rear of the van!
Rushing to the side door, to Officer starts to jerk it open as:
No! Don't! Wait!!!
Too late! The door flies open and TWO HUGE GORILLAS leap out, decking the Officer in the process. Grunting and squealing with delight at their new-found freedom, they disappear round the corner of the van.
ANGLE ON FAR SIDE OF VAN
The dazed Officer rounds the van in pursuit, scratches his head, puzzled. The Gorillas have disappeared. In b.g. we now see, printed on the side of the van: BONZO THE GREAT AND HIS MATE, with a picture of them driving a small red car.
They also cause havoc on the putting green at the Golf Club, driving off in Troy's golf cart.
*With thanks to Erik from thegoonies.com*