Heres the also most logical ending to bttf 4.
INT. INDIAN DRIVE-INN THEATER RESTROOM - DAY
Marty is hiding in a bathroom stall with his feet on the toilet seat. In the stall next to him another version of Marty is getting dressed as Clint Eastwood.
Marty sees the other Marty pass the bathroom stall still wearing his Nike sneakers.
EXT. INDIAN DRIVE-INN THEATER - DAY
55' DOC
VIA CON DIOS!
A gun is fired in the air by Doc several times. The Delorean starts lighting up and enters the vortex right before smashing into the Indians painted on the drive-in screen.
'55 DOC runs closer to the screen, yelling euphorically!
55' DOC
Ya-Haaaaaaaaa!!!!!!!!
Marty steps out of the bathroom.
MARTY
Doc!
'55 Doc turns, sees Marty and Freaks out!
'55 DOC
YAAAAAA!!!!!
'55 DOC points the gun towards Marty
55' DOC
But I just sent you to the past!
Marty looks at the drive-inn screen.
MARTY
I know doc. But now I'm back again from the Future and I need your help!
'55 DOC drops the gun and staggers back. clutching his chest
MARTY
Not again Doc...
'55 DOC has a look of acceptance and stands up straight
55' DOC
Right!
Marty and Doc walk behind a giant boulder to see the Delorean.
INT. DELOREAN - DAY
'55 DOC gets into the Delorean and shuts the passenger gull-wing door.
'55 DOC
This is the most exciting moment of my life Marty! I'm about to travel through time!
Marty in the driver seat enters a date into the time display. OCT 26, 1985 08:00 AM.
'55 DOC [CONT'D]
We need to find a nice smooth path to get up to 88 MPH
MARTY
No Doc..where we're going we don't need roads.
Marty flicks a switch and the Delorean hovers into the air.
EXT. DELOREAN - DAY
The delorean goes forward flying through the air and turns around to the camera and vanishes.
FADE OUT:
SUPERIMPOSE: TO BE CONTINUED