Software start-up failures are often explained with poor business model, market issues, insufficient funding, or simply a bad product idea. However, inadequacies in software product engineering are relatively little explored and could be a significant contributing factor to high start-up failure rate. In this paper we present analysis of 88 start-up experience reports. The analysis is presented in a form of three anti-patterns illustrating common symptoms, actual causes, and potential countermeasures of engineering inadequacies. The three anti-patterns are: product uncertainty comprising of issues in requirements engineering, poor product quality comprising of inadequacies in product quality, and team breakup comprising of team issues. The anti-patterns show that challenges and failure scenarios that appear to be business or market-related can actually originate from inadequacies in product engineering.