$ rake
bash: /c/Ruby23/bin/rake: c:/Users/Justin/Projects/rubyinstaller/sandbox/ruby23_mingw/bin/ruby.exe: bad interpreter: No such file or directory
On my machine there is no user Justin, this is likely this way from the machine where the installer was built.
For me it's fixable by changing the first line of the rake command to #!/c/Ruby23/bin/ruby.exe or (because it's in my PATH) #!ruby.exe