Sobre o FAQ sobre wikidot oficial de Back to the Future II, Robert Gale (co-roteirista do filme e Diretor) descreveu as 99 trilhas de fogo assim:
Q. What is the significance of the pair of "backwards 9's" of fire left behind when the DeLorean is struck by lightning?
Gale : When the big bolt of lightning hits the DeLorean, it sends the flying vehicle spinning on its axis. As we already know, the DeLorean leaves fire trails behind it when it travels through time. Since in this case, the car was spinning, the fire trails are left behind as spirals instead of the usual straight lines left behind when the car is moving straight ahead.
Q. How could the DeLorean travel through time when it gets struck by lightning if it isn't going 88 miles per hour?
Gale : The sudden rotation of the DeLorean from the lightning hit accelerates it to 88 miles per hour when it spins.
Esta citação parece ter sido obtida (literalmente) da Revista Oficial do Fã Clube da BTTF, número 3.