When Baby Smurf (Gargamel) puts down the bomb on the side of the well, the minute hand on the clock is between 9 and 12 and the hour hand is slightly on the 6. In the next shot where Gargamel sets the time on the clock, the time has changed before he sets the time on the clock to 7. Then when he's raising the bucket to the top, the time on the clock has changed and the Roman Numerals are gone.
References to the fictional Cactus Petrifidous (whose juice turns the Smurfs into stone) are made in "The Baby Smurf." However, cacti (which are native to the Americas) were unknown to Europeans until the 17th century. The background of the Smurf cartoon series is the late Middle Ages (circa 14th-15th century), early for the understanding of cacti in Europe.