What are the errors made by English speakers when learning Italian language as a second language?

Answer 1

There are many common errors more or less universal among native English speakers learning Italian.

There are the grammatical ones, where many English speakers forget to have agreement (person and number) with nouns and adjectives. English speakers also frequently use the wrong preposition, or omit it where is usually is (especially when using the infinitive).

For Americans learning Italian, the hardest things with pronunciation are the rolled "r" and adding diphthongs to the end of a word that shouldn't have it (e.g. Americans saying words ending in "o" such as "questo" frequently have an "o" sound that is much longer than a native Italian would say it. The ending vowel should not be dragged out as is common to do in many American accents)

Answer 2

The list is endless. Basically, errors are made whenever English doesn't have a structure like that or doesn't do something the same way. For example:

1. conjugating verbs
2. all the different verb forms (passato, futuro, imperativo, condizionale, subjuctivo, etc.)
3. adjusting nouns and adjectives to masculine/ feminine/ singular/ plural
4. compound pronouns (e.g. 'glielo detto')
5. grammatical gender (kind of why is a plate 'he' and a cup 'she', and what is 'lo'?)
6. compound articles (e.g. dello)
7. the formal and informal 'you' ('Come si chiama' vs. 'Come ti chiami')
8. sentence structure
9. pronunciation