Amanda Bynes -- COPS GOT NOTHING ... When It Comes to Drugs

The Amanda Bynes drug case is falling apart ... FAST ... because the cops have absolutely NO HARD EVIDENCE that Amanda was ever in possession of weed, this based on information TMZ has obtained from law enforcement.

An NYPD official told TMZ ... the police report mentions NOTHING of any marijuana recovered at the scene. According to the report, cops saw Amanda throw what they believe is "drug paraphernalia" out the window. The report also says cops smelled "a strong odor of marijuana."

Based on multiple calls to law enforcement and others ... it appears NO DRUGS were recovered ... and that's what Amanda has been saying all along.

As for the alleged bong ... it's almost certain it will never be admitted into evidence. TMZ broke the story ... our producer spotted glass remnants on a sub-roof Tuesday and then called police and asked if they had inspected it. He was told they hadn't, and was asked for the location where the glass was found. Cops arrived a short time later and presumably checked the sub-roof.

Here's the problem ... No one knows if anyone tampered with the glass remnants which sat for days, in the rain. The chain of custody has been irretrievably broken and it's virtually certain the glass would not be admissible into evidence.

Short story ... even if prosecutors try to nail Amanda for reckless endangerment by throwing something out the window -- cops say she confessed to throwing a vase but she denies it -- there's no physical evidence of what was allegedly thrown. We've spoken with several lawyers who say it will be extremely difficult to convict her on reckless endangerment without physical evidence.

Short story -- if you're betting on this one, Amanda seems to be a pretty safe gamble.