weird glitch in mc 1.2.5

i was tryin to play 1.2.5 because yes and weird glitch happened (I fixed it after) does anyone know how tjis happened? (also yes i freaked out and installed bandicam that was all i could think of)
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By Bandicam Screen Recorder (www.bandicam.com)

[@oliveregas3878]

Note: this is NOT AN ARG. This is an actual glitch that happened to me