Like the title says, what is the oddest/weirdest item you have seen on the field after a match?
The weirdest things I have seen were a Vex flag (this was before the colored plates) that had been chewed into two pieces, probably by some gearing and an entire side of a drivetrain of a robot.
An omni wheel, a couple collars, and an axle … but all the robots were still driving without a problem.
It turned out to be a team that had 6 wheels who lost the wheel. But still, it panicked everyone.
Mostly just small stuff like nuts and bolts, but I have seen batteries and wheels fall off.
I think that I saw a motor dragging behind a robot once.
I haven’t seen entire mechanisms fall off, But I’d like to (On my opponent’s alliance in playoffs ;)).
I would have to say the weirdest thing that I’ve seen is when @RLA111 lost a wheel from his flywheel whenever his lift engaged, though I believe it ended up going outside of the field so it wasn’t technically left on the field after the match.
Also, a few competitions ago a robot basically fell apart during a match against us. It was a small robot similar to the claw bot except with a plastic scoop to score balls. The scoop and arm were not secured properly so every time they hit something pieces of their robot fell off and were left there throughout the field at the end of the match.
The turret of a local team had fallen off in a few games last competition. It dragged behind them the majority of the match still spinning.
During sack attack, there was a new team that had a small Omni drive and was getting in our way, so we picked them up and put them in a trough. It was completely illegal, but all in good fun and during a practice match.
Our first robot in toss up pulled itself apart when attempting to lift. The slider of the scissor slid right off and parts flew everywhere.
Well last year in Skyrise I had an alliance partner that had a 12" or so rack and pinion lift with a hook or something on their 8" wide robot. In the match, they apparently lifted their lift too high, so it fell off the rack and pinion because there was no hard stop…
Then in a match this year, the opposing alliance lifted, but the lifted robot’s conveyor snapped off and fell on the ground, There was debate over whether or not it was a lift since part of the robot was on the ground, but it was eventually counted as a low lift.
Once i saw a cortex after a match
This was an interesting and funny situation, however I think my favorite thing we have left on the field was the chain conveyor belt on our skyrise robot last year that was torn off by another robot and dragged behind our robot like a dragon tail
and also… no more flying flywheels for us XD
Definately Tabor’s human flesh anti-slip mat. (If you don’t get it join BnS)
A robot.
The match ended and the just walked away.
They eventually came back and got it.
I just remembered that I saw a linear puncher ball holder fall off last competition.
I’ll one up you on this one 
I was reffing a tournament and we (the ref staff) had constantly reminded teams not to touch anything at the end of the match until we told them to (in order to ensure that the scoring was accurate).
Well, after one of the matches one of the refs (coughmecough) forgot to tell the teams to pick up their robots after we had scored the match. The other ref and I walked to the next field to get the next match going, and right before the new match started realized that all four teams from the previous match were still waiting for the go-ahead to pick up their robots.
Whoops 
Major props to the teams, though, for being patient with us, seeing the humor in it, and following the rules we had outlined!