It was there, it just wouldn't drop into place.

I have seen (on one of the YouTube ATC channels) a comercial jet (747, IIRC) that DID lose one of its main landing gear on take-off. Another pilot (in another jet) saw the wheel bounce across the runway.

That plane continued on its way and landed normally. It was just one wheel of a four-wheel truck/assembly (of which a 747 has 4 sets).

It didn't literally lose the gear, there was a mechanical issue that prevented it from engaging.