Yer your right, in the ET film a KZ1 was used.
But later on the ET shop bikes were all made from Hi-ten Steel frames not Cr-Mo frames like the KZ1.
I think there were 3 variants,
1) Appolo ET (Toys-R-Us version)
2) Kuwahara ET with low end parts
3) Kuwahara ET with High end parts (Dia Compe, Suntour etc)
I have ssen genuine Kuwahara ET's with Gold parts where many shops fiited the standard ET with upgraded parts from New.
Don't mind if I'm corrected on the above, as its just information I have read or heard.
I dont mind seeing a KZ1 done in ET colours as a tribute to the film.
Check out link below for more information:
www.dreamgate.ne.jp/kuwahara