hmm. that bridge is the first object in the objects list for Arhnem, too. many a time I accidentally placed that monstrosity and had to try to delete it.
Is it there if you zoom out from within the editor?
I think the Arnhem Bridge is the first object in the first set of objects, so it's the default object when BA can't find what it's actually looking for.
Have you added in any new user objects, but possibly not included them in your additional data folders? Check through all of your current map objects to be sure that everything is definitely what you want (hold shift in Editor mode, and BA will tell you what you've placed on that square). Given that it's appearing way off map, I wonder if you accidentally dropped something off the map, where the Bridge is?
I remember trying to do something 'clever' to the MP version of Ortona once, which for some bizarre reason converted about 10 single-square objects to Arnhem Bridges (not a pretty sight!). Once the offending objects are deleted, everything will work great.