Here are the notes I took while my son and I each built Fling. I ran into most of the same things you did:
Fling Manual Findings:
I’m keeping a list of things I note as I go. What I list may not necessarily be a “mistake” per se, but could just be something to keep in mind.
Step 22 and 29: Show using a 1.5 pitch standoff. These are not included in the SuperKit itself, but a 1 pitch standoff should work fine.
Step 51 is missing the standoffs added in Step 48.
Step 102: Parts list shows 1x2 Corner Connector but needs a 1x2 Offset Corner Connector
Between Steps 105 & 106, a 1x8 support beam just appears on the robot with no mention in the instructions. There is space for two of these beams on the robot.
Step 114: only lists 1 rubber band, but 2 are shown. The mechanism isn’t really functional with only one rubber band. BUT: this is a great intro for kids into testing simple changes to a robot’s mechanisms.
Steps 116-117 again show 1x2 Corner Connectors in the parts list, but use 1x2 Offset Corner Connectors in the build instructions (only the offset would fit here anyway). It also shows needing 2 of them, but you only need 1.
Step 120 has a plastic shaft unaccounted for appearing out of nowhere and is necessary to drive the actual mechanism. I assume there should be a 12T gear there since nothing else will likely fit. I ended up going back to Step 117 and adding a capped shaft and 12T gear. That seems like it’s working for now.
Step 121 shows installing the catapult motor. Step 122 shows that it’s plugged in (assuming port 4 since it was previously empty). Instructions are missing a step between 121 and 122 where you plug in the motor.
Steps 122 and 124 show adding washers behind the wheels. I recommend spacers here. The washers don’t really prevent the wheels from rubbing against the frame. The wheels will be canted slightly when using the plastic shafts, but otherwise are fine.
The catapult, all of which both of my sons and I built individually, was not functional until we moved the base of the linkage to ensure the bushing was underneath it instead of above it. And made sure that the shafts did not protrude into the space where the linkage would rotate.