I wanted to post these here first since I wasn't sure if they were errata or excluded on purpose. The following are Mechs llisted as available in the MUL faction lists (and fairly common-ish), but not in the Tukayyid Supplement lists. Just let me know if any of these should be added to the errata thread.
Battle of Tukayyid Supplemental, PDF
p. 10, Heavy Mechs:
Add EXT-4D Exterminator
p. 11, Assault Mechs:
Add THG-11E Thug
Add HGN-732 Highlander
(only royals are included)
p.12, Medium Mechs:
Add VL-2T Vulcan
p.13, Heavy Mechs:
Add QKD-4H Quickdraw
Add GHR-5H Grasshopper
Add GHR-5J Grasshopper (a field refit in TROs)
Add GLT-3N Guillotine
p.13, Assault Mechs:
Add LGB-7Q Longbow
Also, the following are included in the main Tukayyid book's Clan 2nd-line Heavy Mechs (p. 30), but not in the Supplement's Clan 2nd-line Heavy Mechs (p.10):
Crossbow Prime
Mad Dog C
Summoner Prime