First thing, there is not such thing as Latin American Spanish as a single variety. In fact, the quality you mention, vosotros is pretty much the only thing that is done in Spain and Africa that's not done anywhere in Latin America. For instruction manuals, this will never be an issue, as they will either use impersonal infinitival commands, or they will use singular commands with tú/vos/Vd.
The only other potential exclusively-Spain grammatical indicator I can think of would be usage of synthetic pluperfect (Yo ya limpiara la casa cuando volvió mi esposa) or of postpositioned object pronouns in declarative sentences (Voyme en seguida, Enviételo ayer). But these are quite exclusive to the northwest of Spain and accordingly won't ever show up in anything modern destined to a wide audience.
There are a few vocabulary words that are particular to Spain, but even then, they aren't perfect. Probably ordenador would be your best bet.
Everything else I can think of will identify something as being from some part of Latin America, but they don't apply at all to the entirety of the continent.
In parts of Central America, based on hearing my friends from there talk, there is a strong preference for true passive voice (ser + part.) over the fake passive (se + 3rd pers). But at what level it becomes indicative, that's hard to say. Many manuals are translated, and so tend to be heavier on true passive due to less-than-perfect translations.
In Argentina, Uruguay, and a few other pocketed areas, you'll see the pronoun vos used instead of vosotros. In Argentina, vos has the same sociolinguistic status as tú elsewhere, and will be used in an instruction manual. This will sound as weird to a Mexican as vosotros (in other words, they'll understand, but they don't use it).
Vocabulary wise, it's hard to pin down specific words that you might see in a more formal document like an instruction manual as many of the words that seem characteristic of parts of Latin American are used in some (if a small) part of Spain depending on migration patterns.