Asphalt on some roads and roofs becomes soft and sticky. This can be messy, and can cause some damage. These surfaces can get very, very, hot because black absorbs heat.
Uneven thermal expansion around windows, chimneys, flashing, skylights, and gutters can cause leaks when it rains.
Cars can overheat too. It is harder to cool off the engine and its parts during extreme heat; batteries can go bad quicker, the engine can overheat easier if fluid and coolant levels are not adequate, hoses become soft and can blowout easier, under-inflated tires can over heat easier and blow out.
People who are very young or who are over age 65 are more prone to heat stress; there are many reasons for this but mainly their bodies are not as efficient at cooling down.
Hot, hot, hot: It can get well over 150 F inside of vehicles that are parked; which is why even with cracked windows and parking in the shade does not help much, and a good reason why people and pets should not be left inside a parked vehicle. It is also possible to get thermal burns from vinyl seats, door handles, and steering wheels.
Hot and hotter: Sidewalks can be hot enough to burn bare feet, including pet paws-don't walk dogs on any sort of pavement during a heat wave. Metallic surfaces hold heat; metal slides can burn kids. Grasping a metal hand rail can burn your hand.
Heat waves can cause microorganisms to grow rapidly in water; lakes and ponds are especially susceptible to problems with bacteria, parasites, and amoebas. An amoeba called Naegleria fowleri loves warm water in my area; 3 years ago 6 young men died from the brain infection caused by this critter. The public lakes, rivers, and even the ocean water near beaches have their water tested weekly during hot weather where I live. It is not uncommon for some of them to be closed due to high bacteria counts.