How to see contents of "/.Trashes/501"?

Yes. See the following:

Enable Finder to Show Invisible Files and Folders

Open the Terminal application in your Utilities' folder. At the prompt enter or paste the following command line then press RETURN.

defaults write com.apple.finder AppleShowAllFiles TRUE

killall Finder

To turn off the display of invisible files and folders enter or paste the following command line and press RETURN.

defaults write com.apple.finder AppleShowAllFiles FALSE

killall Finder

Alternatively, you can use one of the numerous third-party utilities such as TinkerTool or ShowHideInvisibleFiles - MacUpdate.

You might try preceding the command lines with "sudo." For example sudo ls -al might do the trick if you are already in the correct location. However, some system folders are protected even against the Admin user by the SIP. It would be easier just to delete the trash folder along with everything in it. Disk Warrior may even get rid of them for you by using its other tools. My system does not allow me to even access the folder as it is nor to list its contents.

How did these corrupt files get into the trash? How did you determine they were corrupt. It may be that Disk Warrior is wrong about them being corrupt. Are you experiencing problems that you have reason to believe is caused by what DW reported?

There are several trash folders.

There is ~/.Trash

and there is /.Trashes/501

BE CAREFUL when issuing any command that remove files, especially when also using sudo.

When using rm, there is no undo!!!

To remove ALL the contents in /.Trashes/501

you would use

sudo rm /.Trashes/501/*

CAREFUL!!!! If a space creeps in after the /, you would be trying to erase ALL THE FILES in your drive! (even it would not work, this is something that causes me shivers...)

DW is pretty old now. The way it identifies corrupt files is based on content. System files may contain data that includes characters the DW deems corrupt even though they are not. A so-called false positive. Anti-malware can report similar unknown characters when evaluating whether a file is a virus or not. If your system is fully functional then I would tend to doubt the veracity of DW's report or corruptions. I would leave well enough alone.

Why? Normally, you can see what is in the Trash by clicking once on the Trash icon in your Dock.

There are two command lines. Your first choice is the correct one. If you wish you can simply use copy and paste to avoid possible typo errors.

Thanks. using sudo works, but does not show contents of Trash.

If sudo ls -al /.Trashes/501 or sudo ls -al /.Trashes/ does not show any files, then there aren't any files in those folders.