The circled devices are typically 0.1uF caps on the VCC, AVCC, or Aref pins.
I don't think it would be a good idea to have external pullups on I2C lines installed on the Arduino board. Many devices you will connect to have their own pullups, and doubling up on pullups could lead to excessive currents. The DS3231 RTC module for example has its own 4.7K pullups on SDA and SCL, which is plenty. Better to add them if and when you need them.
I don't think it would be a good idea to have external pullups on I2C lines installed on the Arduino board.
The internal pullups very often do not meet the specifications for reliable communication. They are too large.Doing so is required by some circumstances. And some Arduino boards have pullups already installed (the Due, for example).Under other circumstances, external pullup resistors need to be removed, and I've run into both situations. Each I2C device is different and every new collection of them should be evaluated independently.
None that I have looked at have external pullup resistors for the I2C lines.
Don't forget that the I2C pins on an ATmega328 chip are also/normally analog inputs, where the strong-ish pullups specified by I2C would be pretty undesirable...
What is meant by strongish pullups?
A "weak pullup" is usually a pretty large resistor (the AVR internal pullups are supposed to be about 40-50k ohms), usually used on a CMOS digital input that doesn't need any "current" to change state. You can apply nearly any sort of external signal, and it will over-power a "weak pull-up", because they're "weak."A "strong" pullup is a much smaller resistor (2.2k or less, usually) designed to provide actual current to circuitry that requires it. Notably TTL Logic and bipolar transistors. They require "strong" signals to override them.The 4.7k resistors generally recommended for I2C are in between those values. definitely strong enough to interfere with an analog signal (it would act like a voltage divider, with exact behavor dependent on the impedance of the analog source.) So "strong-ish" - "somewhat strong."