Amazon

Very professional experience. Work with many technologies. Treated the same as a normal engineer. Good pay.

Funny story, none of these were 'if's for me.

If your mentor leaves mid-internship, have fun being given a hard project in the last part of your internship while getting scolded for asking questions on complex things.

If you are matched with a senior-level SDE after your mentor leaves, enjoy receiving no help, then questions on why little progress has been made.

If your manager forgets the midpoint review, good luck because it will end with you getting no return offer due to "no progression on feedback".

If your manager apologizes for everything that went wrong and realizes that the decision made for your no-offer might need to be re-evaluated, but has sealed your fate before you even get to the final meeting due to company policies, start searching for job applications.

Fix the company bureaucracy.