I made this Quake 3 terrain map and it loads in DarkPlaces just fine:
Image: www.quaketastic.co..._prototype1.gif
Detail: www.moddb.com/mods...type-quake-1-sp
I tried to make a Quake 3 pure version of this map and apparently Quake 3 hates autosprite2 when made from an .ase model for reasons unknown. And for some reason, .md3 and .obj are a no go. I used q3map_surfaceModel to place those several hundreds of trees and thousands of plants, so it has to be an external model. I use autosprite2 because each one is just 2 triangles. 1 model -> 2 triangles = a great deal!
I have made other DarkPlaces maps like this one:
Image: www.quaketastic.co...ots/mtstart.gif
Link: www.moddb.com/mods...test-1-quake-11
and then later converted to pure Quake 3 ...
Link: www.moddb.com/mods...3-quake-sandbox
(That one is too big for Open Arena .. Quake Sandbox which is a fork of Open Arena -- loads it fine.)
Or ...
This Pixel Art Neon Sign conversion ...
Image: media.moddb.com/ca..._neon_signs.gif
Link: www.moddb.com/mods...dbox-open-arena
Quite the shame that autosprite2 and .ase seemingly don't play nice together at all, but DarkPlaces makes it work somehow.
Edited 5.48 minutes after the original posting.

@Baker - Yep, deformVertexes autosprite2 has issues when used with models in a map. Depending on how you have made the model, other shader attributes can also have issues.

If you use r_showtris 1 you can see the "bug". The triangles appear to be rendered wrong. It is possible this is a compile issue. I have only tested this with maps compiled with q3map2.

Personally, I always test and re-test before committing to any design decision for this very reason.

You could always log a bug report or a patch with your Q3A Engine of choice to see if it can be resolved (assuming the issue is not with q3map2).

Thanks for confirming that this something I can't fix without editing the Q3 engine because is known confirmed issue.
I'm primarily targeting DarkPlaces, but since Quake SandBox can load the maps because -- I'm guessing --- some engine modifications to support larger maps than OpenArena / Q3 does at least out of the box I occasionally like to build targeting Quake 3 and try it in Quake SandBox to see how Q3 reacts/renders the map.
(I already did the r_showtris stuff to look at the triangles during testing to see if I could picture what exactly was wrong with the rendering in Q3).