This may have been obvious to everyone except me, but turns out those arrows point where the next balloons are coming from. And later on show you the sequence that they'll follow.
Oh, and another tip to beat 18 days - on Day 1 get 1 point in acceleration which will get you the distance achievement on your next run. Then get glider, and get the height achievement. Then Ramp height 3 and get the time achievement. Finally, Accel 3, and go to Stage 2 to get the bonus cash for height. And, importantly, do NOT upgrade gradually if you can help it. You'll pay way more since you pay for every level you buy. Put all your cash into one thing each day, don't spread it.
Tip for completing in 18 days - even though you need all the acheivements to access the last level, you don't need to complete them all for each stage before progressing. It's fairly easy to hit the height one on stage 3 before the speed one on stage 1, for example. And the bonus cash helps you build faster.
Oh, and for people trying to reduce the number of days taken, two tips.
1. Do not upgrade gradually. Try to upgrade in bigger steps. For example, it costs $100 to upgrade something by three, but if you upgrade it by 2 for $60, that third step will still cost you another $100.
2. Don't worry about completing all achievements on a level before moving to the next one.
Too easy really. But fun. Didn't even have acceleration maxed out.
For 6k, tilt up when you launch and blast all your rockets in one go, getting speed and altitude. Then just adjust your angle until you see your speed is going down very slowly. And, err, that's it. Just glide. I was on about 5600 before I even hit the water first time.
Important - your headstand score ONLY doubles if you hold it until the flip is completed (you'll get the prompt on-screen giving you the points for the flip.
Couple of tips for hard badge :
The rocket contiinues to boost you in the direction it's pointing AFTER you jump
Doing a flip doubles the trick points.
You just need one long headstand plus maybe one after you land.
Ok wow... Just completed lvl 10 but it took a fairly long time. And I knew all the countries apart from some of the new ones before playing, so you need a good base knowledge before you start or it'll take forever.
Completed it on Day 3 but took me a while to get a good enough haul on Day 1. Aim for 2k aafter first day and you're on the right track. I ended up getting 8k, but it's mostly luck.