While it certainly may have been unconsidered of the group to ignore Cisco's vital part in them knowing about the book that Oliver drew in their discussion about it, as it was based on Cisco's vibe in the first place, that alone can't be categorized as a "Goof" by any stretch. The important part in that discussion wasn't so much how they came to this knowledge, but rather how that would help them.
Even in the chaotic history of Arkham Asylum, it would never make sense to place an unlocked lab/weapon storage facility in the hallway amidst prisoner cells.