While I was playing Falaise Pocket COOP 64 as Canadian forces, I noticed the antenna flag in the universalcarrier_bren vehicle glitches.
Found out that it uses different positions than the other variants.
Fixed it by changing it to universalcarrier_vickers variant value:
ObjectTemplate.addTemplate antennaYpennant
ObjectTemplate.setPosition 0.412/0.59/-1.163