My novel is set in the near future, and the first chapter takes place in a water park and there’s nothing to indicate that it’s anything other than present day. So, when they get in the car it’s a bit of a shock to be suddenly Sci-Fi. I’m wondering what little clues might be present that indicate a futuristic setting, to show right away and sprinkle throughout the beginning?
An I-Phone 12 or maybe seeing a jet propulsion drone delivering a package, or a holographic watch, or a compact under water breathing apparatus, or nanites that one of the kids had injected into his body to protect him from radiation, and as a consequence, from sun burn as well. Those ideas said, be careful of what you use as within 5 or 10 years, your SF clue of the future, may not be so much the future any more.
Your book will be overtaken by events, but perhaps the news of the passing of some famous figure who is currently still alive, or the completion of some large project (Brexit, Korean unification, the Mexican Border Wall) might work. Edit: Or rather than the passing of a famous figure, the results of said passing. King William's visit to Canada?
You've already had some sound suggestions, but you could throw in something like a huge holographic projection at the end of one of the pools, making it look like it stretches out to the sea's horizon, or a tropical palm beach.
If your talking the near future, maybe you can go with the car itself. For example, maybe the it's a smart car that can drive itself. I think there are already cars that can automatically brake in emergencies so it would be logical that they would invent a car that can drive itself, maybe even take you to your destination via GPS co-ordinates.
Yes, exactly, the car is self-driving to a limited extent. But that's revealed at the end of the chapter. It comes as a shock that the story is Sci-Fi all of a sudden. So I want to work in more futuristic cues without being intrusive, early and throughout.