Cels Forum

My guess is that the cel is real, but was probably part
of some other larger cel overlay sequence and the numbering
was lost during the process or never filled in (have not 
seen the final season so I really do not know this for 
certain). The last season of SM ended in the last 5 years,
so all the standard animation practices would definitely
be in effect.

However, I do think that the background, like most of the Toei 
cels being released now, is non matching and the errors that 
you see might not have been visible on the original background
and that might be why the cel checkers did not pick up
the error. Then again, it might be that the cel was noticed
by the cel checkers and replaced and that might be why
the numbering problem and the faults exist, since it was
not used. Unfortunately, I do not think anyone can say for 
certain.

In regards to the statement: 
"It may be possible to study the chemical composition of
the cel paint - but I think that would be out of the 
normal collector's league."

I actually do that quite alot on a less scientific level
when I am suspicious of a cel. If possible, I try to find
a reference cel from the series and hopefully from the 
episode of the cel with the same lighting conditions and
compare the exact paints. Since the paints are from a
general stocks, the colors should match exactly. No forger
will probably go through or can do the painstaking effort 
required to match precisely the colors used. If there are
subtle differences in the colors (esp. not the primary
colors) or the consistency of the paint, it is a good 
indications that the cel might be a fake. If you want to be 
more precise, most of the more expensive scanners can do 
densiometric and color spectrum analysis which can give 
you directly comparable results). 

My 2 cents,
Marcus