"over" is a preposition, not an adverb

[isomorphisms]

I can think of some examples where "overly" is used to modify adjectives ("overly easy"), but I'm not sure "over" is ever an adverb---and in your example "The quick brown fox jumped over the lazy dog", it's a preposition beginning a prepositional phrase.

[timtadh]

You are correct -- that is clearly a mistake. Luckily it is not a fatal one the english sentence was merely there to demonstrate the idea of lexing to people new to the idea.