If you don't turn the beam off while moving between digits, you will see "flyback lines" connecting the numbers. The schematic must include a transistor that shorts G1 to -50V during jumps.
The true complexity of a CRT clock schematic lies between the microcontroller and the tube’s deflection plates. Microcontrollers output milliamps at 5V, but CRT deflection plates require tens of volts and sufficient current to move the beam quickly across the phosphor screen. This is where (often based on operational amplifiers like the TL084 or discrete transistor pairs) come into play. Crt Clock Schematic