The error is a lack of a rarity symbol on the bottom of the card
Its not unreasonable for them to fear it
It defines Modern right out of the gate while giving Commander and Legacy players new toys and valuable reprints
Adventurer's Airship Archive Haunt Artful Looter Assassin Gauntlet Atlantean Skirmisher Bag of Holding Baron Strucker, HYDRA Overlord Benthic Biomancer Boosted Sloop Cait, Cage Brawler Carlo, Suave Schemer Chakra Meditation Copycrook Coralhelm Chronicler Currency Converter Customs Depot Cyclonus, the Saboteur Diviner of Fates Doc Ock's Henchmen Doctor Doom, King of Latveria Dreadwing Scavenger Emet-Selch, Unsundered Frontline Sage Furtive Courier Goben, Gene-Splice Savant Gran-Gran Illuminator Virtuoso Improbable Alliance Inspired Sprite Jace Reawakened Jace, Cunning Castaway Kaito Shizuki Kaito, Cunning Infiltrator Kamiz, Obscura Oculus Kang, Temporal Tyrant Kitsa, Otterball Elite Ledger Shredder Locke Cole Looter il-Kor Madame Masque Malcolm, Alluring Scoundrel Mary Read and Anne Bonny Mechan Navigator Mirrodin Besieged Muse Seeker Ninja's Blades Norman Osborn Obscura Alleylurkers Paleontologist's Pick-Axe Pharaoh Rama-Tut Pip-Boy 3000 Pirate Hat Playable Delusionary Hydra Pollywog Symbiote Pollywog Symbiote Prowler, Clawed Thief Rewrite History Rona, Herald of Invasion Scurrilous Sentry Shipwreck Sifters Shoreline Looter Sidar Jabari of Zhalfir Silvergill Peddler Spellbound Dragon Sphinx's Tutelage Suspicious Stowaway Swordsman, Sharp Scoundrel Talion's Messenger Teferi's Tutelage Temmet, Naktamun's Will Teo, Spirited Glider The Destined Thief
Iono, an incredible draw supporter card, came in this set, along with two secret rare versions
