An Inconvenient Truth was a good movie that brought the issue of global warming into our living rooms. The movie was meant to be an introduction to this issue, and a provided basic summary of our current knowledge of the subject.
However, anyone who expects to receive the same amount of scientific detail from a two hour blockbuster as from a library of scientific journals will be disappointed.
Your article is not accurate. An "error" doesn't mean the same thing as an error (note the quotation marks). The judge used the word "error" only because that's the term that the prosecution used.
The judge actually ruled that the film could continue to be shown in public schools (i.e. he ruled in favor of the film). He agreed with defense witness, Dr. Scott, that "Al Gore's presentation of the causes and likely effects of climate change in the film was broadly accurate." The judge also ruled that the film advances four main scientific hypotheses, each of which is very well supported by research published in respected, peer-reviewed journals and accords with the latest conclusions of the IPCC[1] and did not amount to political indoctrination,[2] supporting the Government's decision to issue the DVD to public schools