An MVP exists to answer one question as cheaply as possible: will people actually use this? Too many teams treat it instead as a scaled-down version of the full product, which quietly reintroduces all the cost and delay an MVP is supposed to avoid.
The most common mistake is scope creep disguised as "just one more feature." Every additional feature adds development time without adding validation value, and most of them will be reworked anyway once real users provide feedback.
The second is skipping architecture decisions entirely, on the assumption that "we will rebuild it properly later." Some structure upfront, particularly around data models and authentication, saves painful rewrites once the MVP finds traction.
The remaining mistakes we see regularly: choosing unfamiliar technology to "future proof" the MVP, building for a scale you do not have yet, and failing to instrument the product to capture the usage data that justifies the next round of investment.
Our Product Engineering team builds MVPs with just enough architecture to survive success, so that the version that proves your idea is the version you can actually grow from.