Given error.bat:

c:\test>type error.bat
@echo off
exit /b 123
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Use:

system 'error.bat & exit ERRORLEVEL';;
print $? >>8;;

123
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Note: Because Perl attempts to emulate *nix here, exit codes (ERRORLEVELs) are truncated to 8 bits.

Or, skip using /b:

c:\test>type error.bat
@echo off
exit 123

c:\test>p1
[0] Perl> system 'error.bat'; print $? >>8;;
123
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