How do you usually plan for retirement if you want to travel a lot later?

Travelling need not be expensive, in fact can be cheaper than similar lifestyle in Singapore. Go to places where is much cheaper, having deflation like Chinese cities, South East Asia, Eastern Europe or even further.

Will get some dividend stocks for passive income to fund the travels

Travel alot to where? Do you mean travel all around the world? Even to Artic Antartica? Is that what you want? You can spend a long time traveling within US, Europe, China itself. If travel within Asia, its even cheaper. Once you set a realistic target, then you can plan.

Build up your passive income over the years. I started accumulating REITS and S Bonds a couple of years ago when no one wanted them. Today, it is giving me an average of $50K yearly passive income. This is more than sufficient for my traveling expenses.