To see all kernel extensions on a Mac, just enter this:

$ kextstat

Warning: that list is going to be pretty long. You might want to instead pipe it to less:

$ kextstat | less

More likely, you just want to see the kernel extensions that were not installed by Apple. Easy enough with grep:

$ kextstat | grep -v apple

The -v says, in essence, show me any line that does not have apple in it. On my machine, I get a much shorter list:

$ kextstat | grep -v apple
Index Refs AddressSize   Wired  Name (Version) <Linked Against>
   580 0xffffff7f81077000 0x450000x45000at.obdev.nke.LittleSnitch (3871) <7 5 4 3 1>
  1270 0xffffff7f82681000 0x7000 0x7000 com.parallels.kext.prl_usb_connect (7.0 15106.786747) <32 7 5 4 3 1>
  1281 0xffffff7f82688000 0x5c0000x5c000com.parallels.kext.prl_hypervisor (7.0 15106.786747) <10 9 7 5 4 3 1>
  1290 0xffffff7f826e4000 0x4000 0x4000 com.parallels.kext.prl_hid_hook (7.0 15106.786747) <7 5 4 3 1>
  1300 0xffffff7f826e8000 0xc000 0xc000 com.parallels.kext.prl_netbridge (7.0 15106.786747) <128 5 4 3 1>
  1310 0xffffff7f826f4000 0x4000 0x4000 com.parallels.kext.prl_vnic (7.0 15106.786747) <36 5 4 3 1>

That’s about what I’d expect. This can be a useful way to debug your machine if weird things are happening. Not to mention, there’d better not be any kernel extensions unless I specifically installed them!