Is there a way to get all the markers on Google Maps?
I'm assuming you have multiple markers that you wish to display on a google map.
The solution is two parts, one to create and populate an array containing all the details of the markers, then a second to loop through all entries in the array to create each marker.
Not know what environment you're using, it's a little difficult to provide specific help.
My best advice is to take a look at this article & accepted answer to understand the principals of creating a map with multiple markers: Display multiple markers on a map with their own info windows