Yes, you can have carbs as long as you limit to 20-30 grams of carbs a day. Stating the obvious root veggies such as potatoes, carrots, beetroots are high in carbs (not in the hcg diet approved list), onions too have carbs (approved on the hcg diet list). So are apples that are rich in carbs.
Since it is necessary to eliminate carbs on phase 2 (VLCD), you can still have in low quantity. The motive is to stay in ketosis. So, if you have half an apple in the morning, you can keep rest of the half for night. If so, you’ll have to do a spinach salad, and that would keep you around 30 grams of carbs which is absolutely fine.