At first glance I see avocado & corn, which are a little higher in calories than the other items, and veggies that were likely grilled in oil. Also, looks like this includes the dressing, so that is a chunk of it right there. I see on the website that the base salad is 810, goes to 1040 (salmon), 906 (shrimp) & 1044 (chicken) with the meat addition. That sound like it is a large meat serving for a salad, and it is also likely cooked with some oil.
Things sneak right up on you, even when it looks like something that looks healthy. Good for you for checking, and
for skipping the high fat dressing!