In order to use SDL_perl with FreeBSD you need to use a threaded version
of Perl, because SDL use threads. Therefore you might want to reinstall
Perl, appending the following flags to Configure:

	-Dusethreads -Duse5005threads -des

But remember: Perls support for threading is still marked EXPERIMENTAL.

As a nasty workaround for using SDL_perl with a non-threaded version of Perl, 
you might try to preload the reentrant C library, e.g.:

	LD_PRELOAD=/usr/lib/libc_r.so perl perlfile.pl

But this won't work in any way and might break other things, you should really
prefer using a threaded version of Perl instead.

I'll contact the maintainer of the lang/perl5 port to add an (optional)
perl binary with thread support enabled. As soon as this problem is solved,
I'm going to create a SDL_perl port.