Why is the Total Current Account Balance of World positive and does it mean that the world has a net Trade Surplus? I wondered if it was possible for all countries to have a Trade Surplus - which turns out to be impossible because the total value of imports in the world must be equal to the total value of exports in the world - because one country's export is another's import, and vice-vera. With this information, I can make 2 assumptions:


All countries cannot have a trade surplus simultaneously.
The total trade surplus in the world (sum of C.A.B. of all countries with positive C.A.B.) must be equal to the total deficit. Inversely, the sum of C.A.B. of all countries must be zero.




I looked at the data for the Current Account Balance (2017 estimate) for all countries, from CIA World Factbook. However, contradictory to my assumption, here's what I observed:


Total Surplus (excluding EU from the list) = $1,469,654,370,000
Total Deficit = -$1,103,897,200,000
Net Balance = Surplus + Deficit = $365,757,170,000 


A positive net balance should point out that the world has a net trade surplus - which I wouldn't expect. This can arise because of incorrect assumptions, flawed data or errors in calculation. 



My question is about why I make this observation, or if my assumption is wrong, why and what does the data actually mean?
Since we are not trading with aliens (yet), you are right in assuming the global account balance ought to be zero. Your data contradicts this because it is collected by numerous statistical agencies who differ in their capability and their methods. Examples for different outcomes could arise from:


different degrees of border control. The fact that an export is registered in country A does not mean it is registered as an import in country B.
different capabilities in processing and collecting data. In some development countries, a substantial share of the economy is informal, i.e. outside the scope of any authority. 
different statistical concepts applied.


There are datasets which try to overcome these difficulties by correcting them such that the global account balance is zero.