How can I remove all slide transitions from a Keynote presentation?
I had to do something similar recently; this worked for me:


Use the "Navigator" view (View menu > Navigator), which shows slide thumbnails on the left side of the window.
Show the animation inspector (View menu > Inspector > Animate); it opens on the right side of the window.
Select one of the slide thumbnails (on the left), then press Command-A to select all of them.
Make sure you have the entire slides selected, not content within them. All thumbnails should have yellow outlines indicating that they're selected, and there shouldn't be anything highlighted in the slide view (the middle part of the window). Also, make sure the animation inspector is showing "Transitions" (what happens between slides) rather than "Build In" "Action" "Build Out" (what happens within a slide). If it's not, recheck you have the thumbnails selected not content within a particular slide.
In the animation inspector, click the "Change" button, then choose "None" from the popup menu that appears.