- "The only thing more uncertain than the future is the past."
- —Soviet proverb that intros the script
After the success of Back to the Future, Robert Zemeckis and Bob Gale worked on the problem of a sequel. In the theatrical release, the departure of Doc, Marty and Jennifer was followed immediately by the credits. When the film was released on VHS and Laser Disc on November 30, 1986, "To Be Continued..." was added.
In the first draft, written by Gale and with the working title "Number Two", there were some elements that would appear in the final version released in 1989. As promised at the close of the first film, Doc, Marty and Jennifer traveled into the future to accomplish the mission ("Something's got to be done about your kids!").
While in the year 2015, Marty spotted a sports almanac and was determined to bring it back to 1985 so that he could win bets. Biff stole the almanac and the time machine, and when the travelers returned to 1985, they returned to an alternate timeline where Biff was rich, powerful, and Marty's stepfather. Leaving Jennifer behind, Doc and Marty went back to the day that old Biff gave the almanac to his younger self. Instead of revisiting 1955, however the script called for Doc and Marty to travel to September 20, 1967.
Out of place in 1967, Marty ends up in jail. Lorraine posts his $500 bond and cancels her plans for a romantic weekend with George in San Francisco. Marty realizes that his birthdate is nine months away and that he has, once again, endangered his existence.
No provision was made for a third film. The draft closes with Dr. Brown's advice to Marty that his future hasn't yet been written.
- Thumb pads are prevalent in 2015 as in the film.
- Doc's garage still exists but it is surrounded by an industrial park.
- The scene where Jennifer notices the items in her house are fairly linear to those of the Back to the Future Part II novelization.
- Doc, Marty, and Jennifer arrive on October 7, 2015 at 3:30 pm.
- Doc tells Marty and Jennifer about their kids once they are already in the alleyway in 2015.
- Courthouse Square no longer has streets but giant sidewalks for pedestrians and bicyclers only, with flying vehicles restricted to elevated streets.
- There is a fountain in the duck pond in front of the Courthouse.
- The Courthouse is now the new entrance to the Courthouse Mall.
- Marty and Jennifer have two 17-year-old children, but their names are Norman and Doris.
- The two-level gas station is operated by Nippoco, under the Nippon Oil Company.
- A billboard advertises Vietnam vacations for TWA, instead of US Air.
- The Holographic Imax Theater plays Godzilla 2015 instead of Jaws 19.
- Marty and Jennifer access a pay phone with a computer database that searchs for all retail bookstores within one mile of its location.
- Griff and his gang enter the McDonald's and replicate the same scene between Biff and George on Norman, except this time with computer disks, data cards, and passkey codes. Griff also replicates the "Hello, anybody home" line.
- Marty's birthdate is established as June 20, 1968, and his middle name is Hopkins, based upon a memorable weekend that his parents had at the Mark Hopkins Hotel in San Francisco. When his age is revealed at the checkout counter of the bookstore, he fakes a story that he got a face lift, however in 2015, drastic wrinkle job surgery is possible.
- Jennifer remains awake and explores downtown with Marty, with Doc's plan falling through when they disappear. He goes back to his laboratory to retrieve Einstein.
- Marty finds the almanac, but only the cover is on display. (See below)
- The almanac covers a span from 1965-2014, rather than 1950-2000 and is 5000 pages thick however ultra-thin paper keeps it light. This almanac costs $39.95 before tax.
- Jennifer and Marty live on 1311 Park Lane in Hilldale.
- Marty is seen as his son Norman by Griff outside the McDonald's, which begins the chase scene.
- Marty scrambles into a theater and encounters a concert by Huey Lewis & The News playing material from 1989 that he had never heard of before. The audience consists largely of people forty to seventy years old.
- Marty runs into his brother Dave McFly and his sister Linda McFly, who are Uncle Dave and Aunt Linda to Norman. Dave is given as 55 and Linda is 51 in 2015.
- When the script was written, there was no role for George McFly. Lorraine is a widow in 2015, and when Marty visits the family in 1967, George is away at graduate school in Berkeley.
- Norman had to be going to the hospital to see his grandmother Lorraine
- Doris McFly was 60 pounds overweight and had acne.
- Jennifer and Marty's marriage is more strained, and Marty is more discouraged from the accident and with his life in general. He frequently attempts get rich quick schemes, and Jennifer is struggling to keep the family afloat and deal their poor credit. Although in the made movie Marty's financial problems are mentioned when he is taken in by Needles to participate in an unnamed illegal activity.
Throughout the first draft screenplay, there are many details about items not seen or known about. These items do not conflict with existing canon from Back to the Future Part II.
- In 1967, Doc had another dog that he named Newton.
- A billboard advertises G.E. superconductors.
- People are curious about Jennifer's real cotton clothes.
- An infostore titled The Library - Your Complete Information Connection exists in the square.
- Painted faces are a contemporary fad.
- Phrases: Interface, floatin' on wild juice
- Wild juice might have been an actual beverage with drug-like effects. (precursor to Red Bull)
- At the infostore, the almanac is available in ROM-Cart, ROM-D, Standard-C, Mini-C, or Micro-C. It could also be rented, leased, or downloaded. In order to do this, one needed to acquire a memcap or a baud rate. (precursor to eBooks/Kindle)
- Doc brought some homing devices for Marty and Jennifer so that they wouldn't get lost. However, they were already gone when he returned. (precursor to GPS)
- McDonald's still exists in 2015, this time with no waiting in lines. McWaiters bring the food to the customer.
- Jennifer states she wanted to name her son Norman, after her grandpa Norman.
- Norman attends Hill Valley Remedial School and is failing even remedial classes.
- A Match Made in Space is a miniseries available in all HD Video Formats.
- There was a two percent handling charge for payment in cash.(accurately predicted)
- Apparently pennies no longer exist, as the retail bookstore cashier rounded up to the nearest nickel. (done in Canada in 2013)
- Future currency has rainbow borders and holographic treasury seals. (accurately predicted)
- Other McFlys in Hill Valley include David R. McFly and Mrs. George F. McFly, as seen when Jennifer looks through the directory.
- Marty and Jennifer's future phone number has 8 digits: 299-6-4484
- $2 was needed to make a pay phone call.
- Doc calls Einstein part-bloodhound, because his grandpa was a bloodhound.
- Doc finds a "Ronco Aroma Amplifier".
- Jennifer finds a Transrapid Maglev train that transported people to Hilldale, East Valley, and San Lomas.
- Marty's Huey Lewis concert was a 3-D holographic concert titled "Back in the 20th Century".
- Marty finds a memorial bust of Goldie Wilson.
- Dave's car travels on wheels, which might be a low-income way to transport oneself.
- They pass a monument of William "Bill" Hill, founder of Hill Valley.
- KSERA is a radio station in 2015 that plays 80s and 90s music.
- They pull into the Hill Valley Community Hospital, which had been expanded over the course of 40 years.
- [https://web.archive.org/web/20130313050244/http://www.bttf.com/scripts/Number_Two.pdf] "Number Two" script