The cases that break a naive quiz
More than one capital. South Africa has three, and each holds a different branch of government: Pretoria is the executive capital, Cape Town the legislative, and Bloemfontein the judicial. Bolivia has two — Sucre is the constitutional capital while La Paz holds the seat of government. Côte d'Ivoire's official capital is Yamoussoukro, while Abidjan remains the largest city and economic centre. A quiz with one answer slot marks two of South Africa's three capitals wrong.
The capital is often not the biggest city. Turkey's capital is Ankara, not Istanbul. Nigeria's is Abuja, not Lagos. Brazil's is Brasília, not Rio de Janeiro or São Paulo. Australia's is Canberra, not Sydney. Canada's is Ottawa, not Toronto. The United States' is Washington, DC, not New York. This is the single most common wrong answer in the category, and it is a genuinely useful thing to learn.
Capitals move. Myanmar moved its seat of government to Naypyidaw in 2005–2006. Kazakhstan's capital was renamed Astana, then Nur-Sultan in 2019, then back to Astana in 2022. A quiz built on a stale list will confidently mark the current answer wrong.