The saddle may have just bent the mounting bracket that typically connects the post to the saddle rails. If the rails and springs are bent then with some brute force they can be straightened but I'd replace the connector if that is bent. They are soft steel so I suspect it is bent.
For the bars if they are steel tubing (test with a magnet) then if you can bend them back without kinking the tubing go for it. No harm there. The stem is a different matter. Toss it and get a new one. It's just not worth the risk that it is cracked or that you will crack it during straightening.