Played in a Quick Draft event where my opponent had:
2x Crystal Grotto, 1x Lupinflower Village, 1x Mountain.

On turn 4, he played Sunshower Druid tapping only the Lupinflower Village followed by another Sunshower Druid tapping both Crystal Grottos. While this play clearly left him with an additional red mana, I initially assumed it was just a visual bug (as he should have been able to tap a Crystal Grotto) on the next turn.

On turn 5, my opponent misses a land drop but proceeds to play a Bushy Bodyguard with the offspring cost. This in total should have cost 3G, but my opponent should have had no way to pay 3G with the manabase at the time.