Welcome to the discussions, anthonysan.
There isn't a way within the program to do it, however it IS possible I think. I'll give you some tips to start down that path, and, if you have any questions, just post back here.
First, go to Keynote preferences and, under General Preferences, choose "Save new documents as packages". Next, create a new document (white theme), change the Master to blank, and place three rectangles on the first slide, each with an EASY to define color. (By "easy to define" I mean pick colors that you would be able to discern numerically, for example 100% red, 100% black, 100% green, etc.) Finally, double click inside each shape and add some unique text. I'm using "firstone", "secondone", "thirdone".
Now, save that document, then right-click (two-finger-click, control-click) on it's icon in the Finder. You should see an option to Show Package Contents. Select that and you should then see a few folders and some files. You're looking for index.apxl.zip. Double click that one to unzip it, then put the .zipped version in the trash (Keynote can read either just as well). Now, you should have an index.apxl file.
When you double-click the index.apxl file, you'll have to choose to open it with TextEdit, then search for your unique text "firstone".
Things get more detailed from this point, but it does lead to a potential solution. Let me know if you're following so far, and we can look at the mysteries within they Keynote file 🙂